- title: ECMAScript® 2025 Language Specification + title: ECMAScript® 2027 Language Specification shortname: ECMA-262 status: draft location: https://tc39.es/ecma262/ markEffects: true + boilerplate: + copyright: alternative
About this Specification
-The document at https://tc39.es/ecma262/ is the most accurate and up-to-date ECMAScript specification. It contains the content of the most recent yearly snapshot plus any finished proposals (those that have reached Stage 4 in the proposal process and thus are implemented in several implementations and will be in the next practical revision) since that snapshot was taken.
+The document at https://tc39.es/ecma262/ is the most accurate and up-to-date ECMAScript specification. It contains the content of the most recent yearly snapshot plus any finished proposals — those that have reached Stage 4 in the proposal process and thus are implemented in several implementations and will be included in the next yearly snapshot. Historical snapshots are available at https://ecma-international.org/publications-and-standards/standards/ecma-262/.
This document is available as a single page and as multiple pages.
Contributing to this Specification
This specification is developed on GitHub with the help of the ECMAScript community. There are a number of ways to contribute to the development of this specification:
@@ -49,9 +192,9 @@Contributing to this Specification
Contributing to this Specification
Introduction
-This Ecma Standard defines the ECMAScript 2025 Language. It is the sixteenth edition of the ECMAScript Language Specification. Since publication of the first edition in 1997, ECMAScript has grown to be one of the world's most widely used general-purpose programming languages. It is best known as the language embedded in web browsers but has also been widely adopted for server and embedded applications.
-ECMAScript is based on several originating technologies, the most well-known being JavaScript (Netscape) and JScript (Microsoft). The language was invented by Brendan Eich at Netscape and first appeared in that company's Navigator 2.0 browser. It has appeared in all subsequent browsers from Netscape and in all browsers from Microsoft starting with Internet Explorer 3.0.
+This Ecma Standard defines the ECMAScript 2027 Language. It is the eighteenth edition of the ECMAScript Language Specification. ECMAScript is based on several originating technologies, the most well-known being JavaScript (Netscape) and JScript (Microsoft). The language was invented by Brendan Eich at Netscape and first appeared in that company's Navigator 2.0 browser. Though best known as the language embedded in web browsers, it has also been widely adopted for use outside the browser, including server and embedded applications, and has grown to be one of the world's most widely used general-purpose programming languages.
The development of the ECMAScript Language Specification started in November 1996. The first edition of this Ecma Standard was adopted by the Ecma General Assembly of June 1997.
That Ecma Standard was submitted to ISO/IEC JTC 1 for adoption under the fast-track procedure, and approved as international standard ISO/IEC 16262, in April 1998. The Ecma General Assembly of June 1998 approved the second edition of ECMA-262 to keep it fully aligned with ISO/IEC 16262. Changes between the first and the second edition are editorial in nature.
The third edition of the Standard introduced powerful regular expressions, better string handling, new control statements, try/catch exception handling, tighter definition of errors, formatting for numeric output and minor changes in anticipation of future language growth. The third edition of the ECMAScript standard was adopted by the Ecma General Assembly of December 1999 and published as ISO/IEC 16262:2002 in June 2002.
@@ -79,13 +221,14 @@Introduction
Focused development of the sixth edition started in 2009, as the fifth edition was being prepared for publication. However, this was preceded by significant experimentation and language enhancement design efforts dating to the publication of the third edition in 1999. In a very real sense, the completion of the sixth edition is the culmination of a fifteen year effort. The goals for this edition included providing better support for large applications, library creation, and for use of ECMAScript as a compilation target for other languages. Some of its major enhancements included modules, class declarations, lexical block scoping, iterators and generators, promises for asynchronous programming, destructuring patterns, and proper tail calls. The ECMAScript library of built-ins was expanded to support additional data abstractions including maps, sets, and arrays of binary numeric values as well as additional support for Unicode supplementary characters in strings and regular expressions. The built-ins were also made extensible via subclassing. The sixth edition provides the foundation for regular, incremental language and library enhancements. The sixth edition was adopted by the General Assembly of June 2015.
ECMAScript 2016 was the first ECMAScript edition released under Ecma TC39's new yearly release cadence and open development process. A plain-text source document was built from the ECMAScript 2015 source document to serve as the base for further development entirely on GitHub. Over the year of this standard's development, hundreds of pull requests and issues were filed representing thousands of bug fixes, editorial fixes and other improvements. Additionally, numerous software tools were developed to aid in this effort including Ecmarkup, Ecmarkdown, and Grammarkdown. ES2016 also included support for a new exponentiation operator and adds a new method to `Array.prototype` called `includes`.
ECMAScript 2017 introduced Async Functions, Shared Memory, and Atomics along with smaller language and library enhancements, bug fixes, and editorial updates. Async functions improve the asynchronous programming experience by providing syntax for promise-returning functions. Shared Memory and Atomics introduce a new memory model that allows multi-agent programs to communicate using atomic operations that ensure a well-defined execution order even on parallel CPUs. It also included new static methods on Object: `Object.values`, `Object.entries`, and `Object.getOwnPropertyDescriptors`.
-ECMAScript 2018 introduced support for asynchronous iteration via the AsyncIterator protocol and async generators. It also included four new regular expression features: the `dotAll` flag, named capture groups, Unicode property escapes, and look-behind assertions. Lastly it included object rest and spread properties.
+ECMAScript 2018 introduced support for asynchronous iteration via the async iterator protocol and async generators. It also included four new regular expression features: the `dotAll` flag, named capture groups, Unicode property escapes, and look-behind assertions. Lastly it included object rest and spread properties.
ECMAScript 2019 introduced a few new built-in functions: `flat` and `flatMap` on `Array.prototype` for flattening arrays, `Object.fromEntries` for directly turning the return value of `Object.entries` into a new Object, and `trimStart` and `trimEnd` on `String.prototype` as better-named alternatives to the widely implemented but non-standard `String.prototype.trimLeft` and `trimRight` built-ins. In addition, it included a few minor updates to syntax and semantics. Updated syntax included optional catch binding parameters and allowing U+2028 (LINE SEPARATOR) and U+2029 (PARAGRAPH SEPARATOR) in string literals to align with JSON. Other updates included requiring that `Array.prototype.sort` be a stable sort, requiring that `JSON.stringify` return well-formed UTF-8 regardless of input, and clarifying `Function.prototype.toString` by requiring that it either return the corresponding original source text or a standard placeholder.
ECMAScript 2020, the 11th edition, introduced the `matchAll` method for Strings, to produce an iterator for all match objects generated by a global regular expression; `import()`, a syntax to asynchronously import Modules with a dynamic specifier; `BigInt`, a new number primitive for working with arbitrary precision integers; `Promise.allSettled`, a new Promise combinator that does not short-circuit; `globalThis`, a universal way to access the global `this` value; dedicated `export * as ns from 'module'` syntax for use within modules; increased standardization of `for-in` enumeration order; `import.meta`, a host-populated object available in Modules that may contain contextual information about the Module; as well as adding two new syntax features to improve working with “nullish” values (*undefined* or *null*): nullish coalescing, a value selection operator; and optional chaining, a property access and function invocation operator that short-circuits if the value to access/invoke is nullish.
ECMAScript 2021, the 12th edition, introduced the `replaceAll` method for Strings; `Promise.any`, a Promise combinator that short-circuits when an input value is fulfilled; `AggregateError`, a new Error type to represent multiple errors at once; logical assignment operators (`??=`, `&&=`, `||=`); `WeakRef`, for referring to a target object without preserving it from garbage collection, and `FinalizationRegistry`, to manage registration and unregistration of cleanup operations performed when target objects are garbage collected; separators for numeric literals (`1_000`); and `Array.prototype.sort` was made more precise, reducing the amount of cases that result in an implementation-defined sort order.
ECMAScript 2022, the 13th edition, introduced top-level `await`, allowing the keyword to be used at the top level of modules; new class elements: public and private instance fields, public and private static fields, private instance methods and accessors, and private static methods and accessors; static blocks inside classes, to perform per-class evaluation initialization; the `#x in obj` syntax, to test for presence of private fields on objects; regular expression match indices via the `/d` flag, which provides start and end indices for matched substrings; the `cause` property on `Error` objects, which can be used to record a causation chain in errors; the `at` method for Strings, Arrays, and TypedArrays, which allows relative indexing; and `Object.hasOwn`, a convenient alternative to `Object.prototype.hasOwnProperty`.
ECMAScript 2023, the 14th edition, introduced the `toSorted`, `toReversed`, `with`, `findLast`, and `findLastIndex` methods on `Array.prototype` and `TypedArray.prototype`, as well as the `toSpliced` method on `Array.prototype`; added support for `#!` comments at the beginning of files to better facilitate executable ECMAScript files; and allowed the use of most Symbols as keys in weak collections.
ECMAScript 2024, the 15th edition, added facilities for resizing and transferring ArrayBuffers and SharedArrayBuffers; added a new RegExp `/v` flag for creating RegExps with more advanced features for working with sets of strings; and introduced the `Promise.withResolvers` convenience method for constructing Promises, the `Object.groupBy` and `Map.groupBy` methods for aggregating data, the `Atomics.waitAsync` method for asynchronously waiting for a change to shared memory, and the `String.prototype.isWellFormed` and `String.prototype.toWellFormed` methods for checking and ensuring that strings contain only well-formed Unicode.
+ECMAScript 2025, the 16th edition, added a new `Iterator` global with associated static and prototype methods for working with iterators; added methods to `Set.prototype` for performing common operations on Sets; added support for importing JSON modules as well as syntax for declaring attributes of imported modules; added the `RegExp.escape` method for escaping a string to be safely used in a regular expression; added syntax for enabling and disabling modifier flags inline within regular expressions; added the `Promise.try` method for calling functions which may or may not return a `Promise` and ensuring the result is always a `Promise`; and added a new `Float16Array` TypedArray kind as well as the related `DataView.prototype.getFloat16`, `DataView.prototype.setFloat16`, and `Math.f16round` methods.
Dozens of individuals representing many organizations have made very significant contributions within Ecma TC39 to the development of this edition and to the prior editions. In addition, a vibrant community has emerged supporting TC39's ECMAScript efforts. This community has reviewed numerous drafts, filed thousands of bug reports, performed implementation experiments, contributed test suites, and educated the world-wide developer community about ECMAScript. Unfortunately, it is impossible to identify and acknowledge every person and organization who has contributed to this effort.
Allen Wirfs-Brock
@@ -99,23 +242,39 @@
Introduction
Jordan HarbandECMA-262, Project Editor, 10th through 12th Editions +
+ Kevin Gibbons
+ ECMA-262, Project Editor, 12th through 17th Editions
+
Shu-yu Guo
- ECMA-262, Project Editor, 12th through 15th Editions
+ ECMA-262, Project Editor, 12th through 18th Editions
Michael Ficarra
- ECMA-262, Project Editor, 12th through 15th Editions
+ ECMA-262, Project Editor, 12th through 18th Editions
- Kevin Gibbons
- ECMA-262, Project Editor, 12th through 15th Editions
+ Richard Gibson
+ ECMA-262, Project Editor, 18th Edition
+
+ Ron Buckton
+ ECMA-262, Project Editor, 18th Edition
+
+ Nicolò Ribaudo
+ ECMA-262, Project Editor, 18th Edition
+
+ Linus Groh
+ ECMA-262, Project Editor, 18th Edition
Scope
-This Standard defines the ECMAScript 2025 general-purpose programming language.
+This Standard defines the ECMAScript 2027 general-purpose programming language.
Conformance
A conforming implementation of ECMAScript may support program and regular expression syntax not described in this specification. In particular, a conforming implementation of ECMAScript may support program syntax that makes use of any “future reserved words” noted in subclause
A conforming implementation of ECMAScript must not implement any extension that is listed as a Forbidden Extension in subclause
A conforming implementation of ECMAScript must not redefine any facilities that are not implementation-defined, implementation-approximated, or host-defined.
-A conforming implementation of ECMAScript may choose to implement or not implement Normative Optional subclauses. If any Normative Optional behaviour is implemented, all of the behaviour in the containing Normative Optional clause must be implemented. A Normative Optional clause is denoted in this specification with the words "Normative Optional" in a coloured box, as shown below.
+A conforming implementation of ECMAScript may choose to implement or not implement Normative Optional subclauses, unless otherwise indicated. Web browsers are generally required to implement all normative optional subclauses. (See Annex
Example Normative Optional Clause Heading
@@ -386,7 +545,7 @@Number value
Number type
-set of all possible Number values including the special “Not-a-Number” (NaN) value, positive infinity, and negative infinity
+set of all possible Number values including *NaN* (“not a number”), *+∞*𝔽 (positive infinity), and *-∞*𝔽 (negative infinity)
Infinity
NaN
-Number value that is an IEEE 754-2019 “Not-a-Number” value
+Number value that is an IEEE 754-2019 NaN (“not a number”) value
Grammatical Parameters
ReturnStatement ExpressionStatement -Multiple parameters produce a combinatory number of productions, not all of which are necessarily referenced in a complete grammar.
+Multiple parameters produce a combinatoric number of productions, not all of which are necessarily referenced in a complete grammar.
References to nonterminals on the right-hand side of a production can also be parameterized. For example:
Algorithm Conventions
Algorithm steps may declare named aliases for any value using the form “Let _x_ be _someValue_”. These aliases are reference-like in that both _x_ and _someValue_ refer to the same underlying data and modifications to either are visible to both. Algorithm steps that want to avoid this reference-like behaviour should explicitly make a copy of the right-hand side: “Let _x_ be a copy of _someValue_” creates a shallow copy of _someValue_.
Once declared, an alias may be referenced in any subsequent steps and must not be referenced from steps prior to the alias's declaration. Aliases may be modified using the form “Set _x_ to _someOtherValue_”.
+Evaluation Order
+When complex expressions appear in algorithm steps, these are to be understood as being evaluated in a left-to-right, inside-to-outside order. For example, the step
+is equivalent to
+where the various _tmpN_ aliases are ephemeral and visible only in these steps.
+Abstract Operations
In order to facilitate their use in multiple parts of this specification, some algorithms, called abstract operations, are named and written in parameterized functional form so that they may be referenced by name from within other algorithms. Abstract operations are typically referenced using a functional application style such as OperationName(_arg1_, _arg2_). Some abstract operations are treated as polymorphically dispatched methods of class-like specification abstractions. Such method-like abstract operations are typically referenced using a method application style such as _someValue_.OperationName(_arg1_, _arg2_).
@@ -911,6 +1089,8 @@
- description
- It is used to emphasize that a Completion Record is being returned.
+ - skip return checks
+ - true
1. Assert: _completionRecord_ is a Completion Record.
@@ -930,74 +1110,44 @@ Throw an Exception
Throw an Exception
ReturnIfAbrupt
-Algorithms steps that say or are otherwise equivalent to:
-mean the same thing as:
-Algorithms steps that say or are otherwise equivalent to:
-mean the same thing as:
-Where _hygienicTemp_ is ephemeral and visible only in the steps pertaining to ReturnIfAbrupt.
-Algorithms steps that say or are otherwise equivalent to:
-mean the same thing as:
-ReturnIfAbrupt Shorthands
-Invocations of abstract operations and syntax-directed operations that are prefixed by `?` indicate that ReturnIfAbrupt should be applied to the resulting Completion Record. For example, the step:
+Shorthands for Unwrapping Completion Records
+Prefix `?` and `!` are used as shorthands which unwrap Completion Records. `?` is used to propagate an abrupt completion to the caller, or otherwise to unwrap a normal completion. `!` is used to assert that a Completion Record is normal and unwrap it. Formally, the step
is equivalent to the following step:
+is equivalent to
Similarly, for method application style, the step:
+Likewise, the step
is equivalent to:
+is equivalent to
Similarly, prefix `!` is used to indicate that the following invocation of an abstract or syntax-directed operation will never return an abrupt completion and that the resulting Completion Record's [[Value]] field should be used in place of the return value of the operation. For example, the step:
+When `?` or `!` is used in any other context, first apply the rewrite given in
is equivalent to the following steps:
+can be rewritten to
Syntax-directed operations for runtime semantics make use of this shorthand by placing `!` or `?` before the invocation of the operation:
+which in turn expands to
ReturnIfAbrupt Shorthands
Implicit Normal Completion
In algorithms within abstract operations which are declared to return a Completion Record, and within all built-in functions, the returned value is first passed to NormalCompletion, and the result is used instead. This rule does not apply within the Completion algorithm or when the value being returned is clearly marked as a Completion Record in that step; these cases are:
-
-
- when the result of applying Completion, NormalCompletion, or ThrowCompletion is directly returned +
- when the result of applying Completion, NormalCompletion, ThrowCompletion, or ReturnCompletion is directly returned
- when the result of constructing a Completion Record is directly returned
It is an editorial error if a Completion Record is returned from such an abstract operation through any other means. For example, within these abstract operations,
@@ -1025,7 +1175,7 @@Implicit Normal Completion
Note that, through the ReturnIfAbrupt expansion, the following example is allowed, as within the expanded steps, the result of applying Completion is returned directly in the abrupt case and the implicit NormalCompletion application occurs after unwrapping in the normal case.
+Note that, through
Mathematical Operations
In the language of this specification, numerical values are distinguished among different numeric kinds using subscript suffixes. The subscript 𝔽 refers to Numbers, and the subscript ℤ refers to BigInts. Numeric values without a subscript suffix refer to mathematical values. This specification denotes most numeric values in base 10; it also uses numeric values of the form 0x followed by digits 0-9 or A-F as base-16 values.
In general, when this specification refers to a numerical value, such as in the phrase, "the length of _y_" or "the integer represented by the four hexadecimal digits ...", without explicitly specifying a numeric kind, the phrase refers to a mathematical value. Phrases which refer to a Number or a BigInt value are explicitly annotated as such; for example, "the Number value for the number of code points in …" or "the BigInt value for …".
-When the term integer is used in this specification, it refers to a mathematical value which is in the set of integers, unless otherwise stated. When the term integral Number is used in this specification, it refers to a Number value whose mathematical value is in the set of integers.
+When the term integer is used in this specification, it refers to a mathematical value which is in the set of integers, unless otherwise stated. When the term integral Number is used in this specification, it refers to a finite Number value whose mathematical value is in the set of integers.
Numeric operators such as +, ×, =, and ≥ refer to those operations as determined by the type of the operands. When applied to mathematical values, the operators refer to the usual mathematical operations. When applied to extended mathematical values, the operators refer to the usual mathematical operations over the extended real numbers; indeterminate forms are not defined and their use in this specification should be considered an editorial error. When applied to Numbers, the operators refer to the relevant operations within IEEE 754-2019. When applied to BigInts, the operators refer to the usual mathematical operations applied to the mathematical value of the BigInt. Numeric operators applied to mixed-type operands (such as a Number and a mathematical value) are not defined and should be considered an editorial error in this specification.
Conversions between mathematical values and Numbers or BigInts are always explicit in this document. A conversion from a mathematical value or extended mathematical value _x_ to a Number is denoted as "the Number value for _x_" or
The mathematical function
The mathematical function
The mathematical function
The notation “
The phrase "the result of clamping _x_ between _lower_ and _upper_" (where _x_ is an extended mathematical value and _lower_ and _upper_ are mathematical values such that _lower_ ≤ _upper_) produces _lower_ if _x_ < _lower_, produces _upper_ if _x_ > _upper_, and otherwise produces _x_.
@@ -1095,10 +1246,9 @@Identity
ECMAScript Data Types and Values
-Algorithms within this specification manipulate values each of which has an associated type. The possible value types are exactly those defined in this clause. Types are further subclassified into ECMAScript language types and specification types.
-Within this specification, the notation “Type(_x_)” is used as shorthand for “the type of _x_” where “type” refers to the ECMAScript language and specification types defined in this clause.
+Algorithms within this specification manipulate values each of which has an associated type. The possible value types are exactly those defined in this clause. Types are further classified into ECMAScript language types and specification types.
ECMAScript Language Types
@@ -1201,40 +1351,43 @@
The Symbol Type
The Symbol type is the set of all non-String values that may be used as the key of an Object property (
- Each possible Symbol value is unique and immutable.
- Each Symbol value immutably holds an associated value called [[Description]] that is either *undefined* or a String value.
+ Each Symbol is unique and immutable.
+ Each Symbol has an immutable [[Description]] internal slot whose value is either a String or *undefined*.
Well-Known Symbols
Well-known symbols are built-in Symbol values that are explicitly referenced by algorithms of this specification. They are typically used as the keys of properties whose values serve as extension points of a specification algorithm. Unless otherwise specified, well-known symbols values are shared by all realms (
- Within this specification a well-known symbol is referred to by using a notation of the form @@name, where “name” is one of the values listed in
+ Within this specification a well-known symbol is referred to using the standard intrinsic notation where the intrinsic is one of the values listed in
+ Previous editions of this specification used a notation of the form @@name, where the current edition would use `%Symbol.name%`. In particular, the following names were used: @@asyncIterator, @@hasInstance, @@isConcatSpreadable, @@iterator , @@match, @@matchAll, @@replace, @@search, @@species, @@split, @@toPrimitive, @@toStringTag, and @@unscopables.
-
-
- Specification Name
-
-
- [[Description]]
-
-
- Value and Purpose
-
-
+
+
+
+ Specification Name
+
+
+ [[Description]]
+
+
+ Value and Purpose
+
+
+
- @@asyncIterator
+ %Symbol.asyncIterator%
*"Symbol.asyncIterator"*
- A method that returns the default AsyncIterator for an object. Called by the semantics of the `for`-`await`-`of` statement.
+ A method that returns the default async iterator for an object. Called by the semantics of the `for`-`await`-`of` statement.
- @@hasInstance
+ %Symbol.hasInstance%
*"Symbol.hasInstance"*
@@ -1245,7 +1398,7 @@ Well-Known Symbols
- @@isConcatSpreadable
+ %Symbol.isConcatSpreadable%
*"Symbol.isConcatSpreadable"*
@@ -1256,18 +1409,18 @@ Well-Known Symbols
- @@iterator
+ %Symbol.iterator%
*"Symbol.iterator"*
- A method that returns the default Iterator for an object. Called by the semantics of the for-of statement.
+ A method that returns the default iterator for an object. Called by the semantics of the for-of statement.
- @@match
+ %Symbol.match%
*"Symbol.match"*
@@ -1278,18 +1431,18 @@ Well-Known Symbols
- @@matchAll
+ %Symbol.matchAll%
*"Symbol.matchAll"*
- A regular expression method that returns an iterator, that yields matches of the regular expression against a string. Called by the `String.prototype.matchAll` method.
+ A regular expression method that returns an iterator that yields matches of the regular expression against a string. Called by the `String.prototype.matchAll` method.
- @@replace
+ %Symbol.replace%
*"Symbol.replace"*
@@ -1300,7 +1453,7 @@ Well-Known Symbols
- @@search
+ %Symbol.search%
*"Symbol.search"*
@@ -1311,7 +1464,7 @@ Well-Known Symbols
- @@species
+ %Symbol.species%
*"Symbol.species"*
@@ -1322,7 +1475,7 @@ Well-Known Symbols
- @@split
+ %Symbol.split%
*"Symbol.split"*
@@ -1333,7 +1486,7 @@ Well-Known Symbols
- @@toPrimitive
+ %Symbol.toPrimitive%
*"Symbol.toPrimitive"*
@@ -1344,7 +1497,7 @@ Well-Known Symbols
- @@toStringTag
+ %Symbol.toStringTag%
*"Symbol.toStringTag"*
@@ -1355,7 +1508,7 @@ Well-Known Symbols
- @@unscopables
+ %Symbol.unscopables%
*"Symbol.unscopables"*
@@ -1374,20 +1527,22 @@ Numeric Types
ECMAScript has two built-in numeric types: Number and BigInt. The following abstract operations are defined over these numeric types. The "Result" column shows the return type, along with an indication if it is possible for some invocations of the operation to return an abrupt completion.
-
-
- Operation
-
-
- Example source
-
-
- Invoked by the Evaluation semantics of ...
-
-
- Result
-
-
+
+
+
+ Operation
+
+
+ Example source
+
+
+ Invoked by the Evaluation semantics of ...
+
+
+ Result
+
+
+
@@ -1728,9 +1883,8 @@ Numeric Types
`[x].includes(y)`
- Array, Map, and Set methods,
via
Boolean
@@ -1828,7 +1982,7 @@ Numeric Types
The Number Type
- The Number type has exactly 18,437,736,874,454,810,627 (that is, 264 - 253 + 3 ) values, representing the double-precision floating point IEEE 754-2019 binary64 values as specified in the IEEE Standard for Binary Floating-Point Arithmetic, except that the 9,007,199,254,740,990 (that is, 253 - 2 ) distinct “Not-a-Number” values of the IEEE Standard are represented in ECMAScript as a single special *NaN* value. (Note that the *NaN* value is produced by the program expression `NaN`.) In some implementations, external code might be able to detect a difference between various Not-a-Number values, but such behaviour is implementation-defined; to ECMAScript code, all *NaN* values are indistinguishable from each other.
+ The Number type has exactly 18,437,736,874,454,810,627 (that is, 264 - 253 + 3 ) values, representing the double-precision floating point IEEE 754-2019 binary64 values as specified in the IEEE Standard for Binary Floating-Point Arithmetic, except that the 9,007,199,254,740,990 (that is, 253 - 2 ) distinct NaN values of the IEEE Standard are represented in ECMAScript as a single special *NaN* value. (Note that the *NaN* value is produced by the program expression `NaN`.) In some implementations, external code might be able to detect a difference between various NaN values, but such behaviour is implementation-defined; to ECMAScript code, all *NaN* values are indistinguishable from each other.
The bit pattern that might be observed in an ArrayBuffer (see
@@ -1862,7 +2016,7 @@
1. If _x_ is *NaN*, return *NaN*.
- 1. Return the result of negating _x_; that is, compute a Number with the same magnitude but opposite sign.
+ 1. Return the negation of _x_; that is, compute a Number with the same magnitude but opposite sign.
@@ -1876,7 +2030,7 @@
1. Let _oldValue_ be ! ToInt32(_x_).
- 1. Return the result of applying bitwise complement to _oldValue_. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
+ 1. Return the bitwise complement of _oldValue_. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
@@ -1896,28 +2050,32 @@
1. If _exponent_ is either *+0*𝔽 or *-0*𝔽, return *1*𝔽.
1. If _base_ is *NaN*, return *NaN*.
1. If _base_ is *+∞*𝔽, then
- 1. If _exponent_ > *+0*𝔽, return *+∞*𝔽. Otherwise, return *+0*𝔽.
+ 1. If _exponent_ > *+0*𝔽, return *+∞*𝔽.
+ 1. Return *+0*𝔽.
1. If _base_ is *-∞*𝔽, then
1. If _exponent_ > *+0*𝔽, then
- 1. If _exponent_ is an odd integral Number, return *-∞*𝔽. Otherwise, return *+∞*𝔽.
- 1. Else,
- 1. If _exponent_ is an odd integral Number, return *-0*𝔽. Otherwise, return *+0*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-∞*𝔽.
+ 1. Return *+∞*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-0*𝔽.
+ 1. Return *+0*𝔽.
1. If _base_ is *+0*𝔽, then
- 1. If _exponent_ > *+0*𝔽, return *+0*𝔽. Otherwise, return *+∞*𝔽.
+ 1. If _exponent_ > *+0*𝔽, return *+0*𝔽.
+ 1. Return *+∞*𝔽.
1. If _base_ is *-0*𝔽, then
1. If _exponent_ > *+0*𝔽, then
- 1. If _exponent_ is an odd integral Number, return *-0*𝔽. Otherwise, return *+0*𝔽.
- 1. Else,
- 1. If _exponent_ is an odd integral Number, return *-∞*𝔽. Otherwise, return *+∞*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-0*𝔽.
+ 1. Return *+0*𝔽.
+ 1. If _exponent_ is an odd integral Number, return *-∞*𝔽.
+ 1. Return *+∞*𝔽.
1. Assert: _base_ is finite and is neither *+0*𝔽 nor *-0*𝔽.
1. If _exponent_ is *+∞*𝔽, then
1. If abs(ℝ(_base_)) > 1, return *+∞*𝔽.
1. If abs(ℝ(_base_)) = 1, return *NaN*.
- 1. If abs(ℝ(_base_)) < 1, return *+0*𝔽.
+ 1. Return *+0*𝔽.
1. If _exponent_ is *-∞*𝔽, then
1. If abs(ℝ(_base_)) > 1, return *+0*𝔽.
1. If abs(ℝ(_base_)) = 1, return *NaN*.
- 1. If abs(ℝ(_base_)) < 1, return *+∞*𝔽.
+ 1. Return *+∞*𝔽.
1. Assert: _exponent_ is finite and is neither *+0*𝔽 nor *-0*𝔽.
1. If _base_ < *-0*𝔽 and _exponent_ is not an integral Number, return *NaN*.
1. Return an implementation-approximated Number value representing the result of raising ℝ(_base_) to the ℝ(_exponent_) power.
@@ -1950,10 +2108,10 @@
1. Return -_y_.
1. If _x_ is *-0*𝔽, then
1. If _y_ is *-0*𝔽 or _y_ < *-0*𝔽, return *+0*𝔽.
- 1. Else, return *-0*𝔽.
+ 1. Return *-0*𝔽.
1. If _y_ is *-0*𝔽, then
1. If _x_ < *-0*𝔽, return *+0*𝔽.
- 1. Else, return *-0*𝔽.
+ 1. Return *-0*𝔽.
1. Return 𝔽(ℝ(_x_) × ℝ(_y_)).
@@ -1979,17 +2137,21 @@
1. If _y_ is *+0*𝔽 or _y_ > *+0*𝔽, return _x_.
1. Return -_x_.
1. If _y_ is *+∞*𝔽, then
- 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *+0*𝔽. Otherwise, return *-0*𝔽.
+ 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *+0*𝔽.
+ 1. Return *-0*𝔽.
1. If _y_ is *-∞*𝔽, then
- 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *-0*𝔽. Otherwise, return *+0*𝔽.
+ 1. If _x_ is *+0*𝔽 or _x_ > *+0*𝔽, return *-0*𝔽.
+ 1. Return *+0*𝔽.
1. If _x_ is either *+0*𝔽 or *-0*𝔽, then
1. If _y_ is either *+0*𝔽 or *-0*𝔽, return *NaN*.
1. If _y_ > *+0*𝔽, return _x_.
1. Return -_x_.
1. If _y_ is *+0*𝔽, then
- 1. If _x_ > *+0*𝔽, return *+∞*𝔽. Otherwise, return *-∞*𝔽.
+ 1. If _x_ > *+0*𝔽, return *+∞*𝔽.
+ 1. Return *-∞*𝔽.
1. If _y_ is *-0*𝔽, then
- 1. If _x_ > *+0*𝔽, return *-∞*𝔽. Otherwise, return *+∞*𝔽.
+ 1. If _x_ > *+0*𝔽, return *-∞*𝔽.
+ 1. Return *+∞*𝔽.
1. Return 𝔽(ℝ(_x_) / ℝ(_y_)).
@@ -2079,10 +2241,10 @@
- 1. Let _lnum_ be ! ToInt32(_x_).
- 1. Let _rnum_ be ! ToUint32(_y_).
- 1. Let _shiftCount_ be ℝ(_rnum_) modulo 32.
- 1. Return the result of left shifting _lnum_ by _shiftCount_ bits. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
+ 1. Let _lNum_ be ! ToInt32(_x_).
+ 1. Let _rNum_ be ! ToUint32(_y_).
+ 1. Let _shiftCount_ be ℝ(_rNum_) modulo 32.
+ 1. Return the result of left shifting _lNum_ by _shiftCount_ bits. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
@@ -2096,10 +2258,10 @@
- 1. Let _lnum_ be ! ToInt32(_x_).
- 1. Let _rnum_ be ! ToUint32(_y_).
- 1. Let _shiftCount_ be ℝ(_rnum_) modulo 32.
- 1. Return the result of performing a sign-extending right shift of _lnum_ by _shiftCount_ bits. The most significant bit is propagated. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
+ 1. Let _lNum_ be ! ToInt32(_x_).
+ 1. Let _rNum_ be ! ToUint32(_y_).
+ 1. Let _shiftCount_ be ℝ(_rNum_) modulo 32.
+ 1. Return the result of performing a sign-extending right shift of _lNum_ by _shiftCount_ bits. The most significant bit is propagated. The mathematical value of the result is exactly representable as a 32-bit two's complement bit string.
@@ -2113,10 +2275,10 @@
- 1. Let _lnum_ be ! ToUint32(_x_).
- 1. Let _rnum_ be ! ToUint32(_y_).
- 1. Let _shiftCount_ be ℝ(_rnum_) modulo 32.
- 1. Return the result of performing a zero-filling right shift of _lnum_ by _shiftCount_ bits. Vacated bits are filled with zero. The mathematical value of the result is exactly representable as a 32-bit unsigned bit string.
+ 1. Let _lNum_ be ! ToUint32(_x_).
+ 1. Let _rNum_ be ! ToUint32(_y_).
+ 1. Let _shiftCount_ be ℝ(_rNum_) modulo 32.
+ 1. Return the result of performing a zero-filling right shift of _lNum_ by _shiftCount_ bits. Vacated bits are filled with zero. The mathematical value of the result is exactly representable as a 32-bit unsigned bit string.
@@ -2140,7 +2302,8 @@
1. If _y_ is *-∞*𝔽, return *false*.
1. If _x_ is *-∞*𝔽, return *true*.
1. Assert: _x_ and _y_ are finite.
- 1. If ℝ(_x_) < ℝ(_y_), return *true*. Otherwise, return *false*.
+ 1. If ℝ(_x_) < ℝ(_y_), return *true*.
+ 1. Return *false*.
@@ -2210,17 +2373,17 @@
- 1. Let _lnum_ be ! ToInt32(_x_).
- 1. Let _rnum_ be ! ToInt32(_y_).
- 1. Let _lbits_ be the 32-bit two's complement bit string representing ℝ(_lnum_).
- 1. Let _rbits_ be the 32-bit two's complement bit string representing ℝ(_rnum_).
+ 1. Let _lNum_ be ! ToInt32(_x_).
+ 1. Let _rNum_ be ! ToInt32(_y_).
+ 1. Let _lBits_ be the 32-bit two's complement bit string representing ℝ(_lNum_).
+ 1. Let _rBits_ be the 32-bit two's complement bit string representing ℝ(_rNum_).
1. If _op_ is `&`, then
- 1. Let _result_ be the result of applying the bitwise AND operation to _lbits_ and _rbits_.
+ 1. Let _result_ be the result of applying the bitwise AND operation to _lBits_ and _rBits_.
1. Else if _op_ is `^`, then
- 1. Let _result_ be the result of applying the bitwise exclusive OR (XOR) operation to _lbits_ and _rbits_.
+ 1. Let _result_ be the result of applying the bitwise exclusive OR (XOR) operation to _lBits_ and _rBits_.
1. Else,
1. Assert: _op_ is `|`.
- 1. Let _result_ be the result of applying the bitwise inclusive OR operation to _lbits_ and _rbits_.
+ 1. Let _result_ be the result of applying the bitwise inclusive OR operation to _lBits_ and _rBits_.
1. Return the Number value for the integer represented by the 32-bit two's complement bit string _result_.
@@ -2289,18 +2452,17 @@
1. Return the string-concatenation of:
* the code units of the _k_ digits of the representation of _s_ using radix _radix_
* _n_ - _k_ occurrences of the code unit 0x0030 (DIGIT ZERO)
- 1. Else if _n_ > 0, then
+ 1. If _n_ > 0, then
1. Return the string-concatenation of:
* the code units of the most significant _n_ digits of the representation of _s_ using radix _radix_
* the code unit 0x002E (FULL STOP)
* the code units of the remaining _k_ - _n_ digits of the representation of _s_ using radix _radix_
- 1. Else,
- 1. Assert: _n_ ≤ 0.
- 1. Return the string-concatenation of:
- * the code unit 0x0030 (DIGIT ZERO)
- * the code unit 0x002E (FULL STOP)
- * -_n_ occurrences of the code unit 0x0030 (DIGIT ZERO)
- * the code units of the _k_ digits of the representation of _s_ using radix _radix_
+ 1. Assert: _n_ ≤ 0.
+ 1. Return the string-concatenation of:
+ * the code unit 0x0030 (DIGIT ZERO)
+ * the code unit 0x002E (FULL STOP)
+ * -_n_ occurrences of the code unit 0x0030 (DIGIT ZERO)
+ * the code units of the _k_ digits of the representation of _s_ using radix _radix_
1. NOTE: In this case, the input will be represented using scientific E notation, such as `1.2e+3`.
1. Assert: _radix_ is 10.
1. If _n_ < 0, then
@@ -2342,7 +2504,7 @@
Implementers of ECMAScript may find useful the paper and code written by David M. Gay for binary-to-decimal conversion of floating-point numbers:
Gay, David M. Correctly Rounded Binary-Decimal and Decimal-Binary Conversions. Numerical Analysis, Manuscript 90-10. AT&T Bell Laboratories (Murray Hill, New Jersey). 30 November 1990. Available as
- http://ampl.com/REFS/abstracts.html#rounding. Associated code available as
+ https://ampl.com/_archive/first-website/REFS/rounding.pdf. Associated code available as
http://netlib.sandia.gov/fp/dtoa.c and as
http://netlib.sandia.gov/fp/g_fmt.c and may also be found at the various `netlib` mirror sites.
@@ -2532,7 +2694,8 @@
- 1. If ℝ(_x_) < ℝ(_y_), return *true*; otherwise return *false*.
+ 1. If ℝ(_x_) < ℝ(_y_), return *true*.
+ 1. Return *false*.
@@ -2546,7 +2709,8 @@
- 1. If ℝ(_x_) = ℝ(_y_), return *true*; otherwise return *false*.
+ 1. If ℝ(_x_) = ℝ(_y_), return *true*.
+ 1. Return *false*.
@@ -2561,7 +2725,7 @@
1. If _x_ = 1 and _y_ = 1, return 1.
- 1. Else, return 0.
+ 1. Return 0.
@@ -2576,7 +2740,7 @@
1. If _x_ = 1 or _y_ = 1, return 1.
- 1. Else, return 0.
+ 1. Return 0.
@@ -2591,8 +2755,8 @@
1. If _x_ = 1 and _y_ = 0, return 1.
- 1. Else if _x_ = 0 and _y_ = 1, return 1.
- 1. Else, return 0.
+ 1. If _x_ = 0 and _y_ = 1, return 1.
+ 1. Return 0.
@@ -2710,7 +2874,7 @@ The Object Type
An accessor property associates a key value with one or two accessor functions, and a set of Boolean attributes. The accessor functions are used to store or retrieve an ECMAScript language value that is associated with the property.
-
The properties of an object are uniquely identified using property keys. A property key is either a String or a Symbol. All Strings and Symbols, including the empty String, are valid as property keys. A property name is a property key that is a String.
+ The properties of an object are uniquely identified using property keys. A property key is either a String or a Symbol. All Strings and Symbols, including the empty String, are valid as property keys. A property name is a property key that is a String.
An integer index is a property name _n_ such that CanonicalNumericIndexString(_n_) returns an integral Number in the inclusive interval from *+0*𝔽 to 𝔽(253 - 1). An array index is an integer index _n_ such that CanonicalNumericIndexString(_n_) returns an integral Number in the inclusive interval from *+0*𝔽 to 𝔽(232 - 2).
Every non-negative safe integer has a corresponding integer index. Every 32-bit unsigned integer except 232 - 1 has a corresponding array index. *"-0"* is neither an integer index nor an array index.
@@ -2724,13 +2888,15 @@ Property Attributes
Attributes are used in this specification to define and explain the state of Object properties as described in
-
- Attribute Name
- Types of property for which it is present
- Value Domain
- Default Value
- Description
-
+
+
+ Attribute Name
+ Types of property for which it is present
+ Value Domain
+ Default Value
+ Description
+
+
[[Value]]
@@ -2841,7 +3007,7 @@ Property Attributes
Object Internal Methods and Internal Slots
The actual semantics of objects, in ECMAScript, are specified via algorithms called internal methods. Each object in an ECMAScript engine is associated with a set of internal methods that defines its runtime behaviour. These internal methods are not part of the ECMAScript language. They are defined by this specification purely for expository purposes. However, each object within an implementation of ECMAScript must behave as specified by the internal methods associated with it. The exact manner in which this is accomplished is determined by the implementation.
Internal method names are polymorphic. This means that different object values may perform different algorithms when a common internal method name is invoked upon them. That actual object upon which an internal method is invoked is the “target” of the invocation. If, at runtime, the implementation of an algorithm attempts to use an internal method of an object that the object does not support, a *TypeError* exception is thrown.
- Internal slots correspond to internal state that is associated with objects and used by various ECMAScript specification algorithms. Internal slots are not object properties and they are not inherited. Depending upon the specific internal slot specification, such state may consist of values of any ECMAScript language type or of specific ECMAScript specification type values. Unless explicitly specified otherwise, internal slots are allocated as part of the process of creating an object and may not be dynamically added to an object. Unless specified otherwise, the initial value of an internal slot is the value *undefined*. Various algorithms within this specification create objects that have internal slots. However, the ECMAScript language provides no direct way to associate internal slots with an object.
+ Internal slots correspond to internal state that is associated with objects, Symbols, or Private Names and used by various ECMAScript specification algorithms. Internal slots are not object properties and they are not inherited. Depending upon the specific internal slot specification, such state may consist of values of any ECMAScript language type or of specific ECMAScript specification type values. Unless explicitly specified otherwise, internal slots are allocated as part of the process of creating an object, Symbol, or Private Name and may not be dynamically added. Unless specified otherwise, the initial value of an internal slot is the value *undefined*. Various algorithms within this specification create values that have internal slots. However, the ECMAScript language provides no direct way to manipulate internal slots.
All objects have an internal slot named [[PrivateElements]], which is a List of PrivateElements. This List represents the values of the private fields, methods, and accessors for the object. Initially, it is an empty List.
Internal methods and internal slots are identified within this specification using names enclosed in double square brackets [[ ]].
@@ -2864,17 +3030,19 @@ Object Internal Methods and Internal Slots
An internal method implicitly returns a Completion Record, either a normal completion that wraps a value of the return type shown in its invocation pattern, or a throw completion.
-
-
- Internal Method
-
-
- Signature
-
-
- Description
-
-
+
+
+
+ Internal Method
+
+
+ Signature
+
+
+ Description
+
+
+
[[GetPrototypeOf]]
@@ -3001,17 +3169,19 @@ Object Internal Methods and Internal Slots
-
-
- Internal Method
-
-
- Signature
-
-
- Description
-
-
+
+
+
+ Internal Method
+
+
+ Signature
+
+
+ Description
+
+
+
[[Call]]
@@ -3113,7 +3283,7 @@ [[GetOwnProperty]] ( _P_ )
The normal return type is either Property Descriptor or Undefined.
- If the Type of the return value is Property Descriptor, the return value must be a fully populated Property Descriptor.
+ If the return value is a Property Descriptor, it must be a fully populated Property Descriptor.
If _P_ is described as a non-configurable, non-writable own data property, all future calls to [[GetOwnProperty]] ( _P_ ) must return Property Descriptor whose [[Value]] is SameValue as _P_'s [[Value]] attribute.
@@ -3202,7 +3372,7 @@ [[OwnPropertyKeys]] ( )
The returned List must not contain any duplicate entries.
- The Type of each element of the returned List is either String or Symbol.
+ Each element of the returned List must be a property key.
The returned List must contain at least the keys of all non-configurable own properties that have previously been observed.
@@ -3234,17 +3404,19 @@ Well-Known Intrinsic Objects
Within this specification a reference such as %name% means the intrinsic object, associated with the current realm, corresponding to the name. A reference such as %name.a.b% means, as if the *"b"* property of the value of the *"a"* property of the intrinsic object %name% was accessed prior to any ECMAScript code being evaluated. Determination of the current realm and its intrinsics is described in
-
-
- Intrinsic Name
-
-
- Global Name
-
-
- ECMAScript Language Association
-
-
+
+
+
+ Intrinsic Name
+
+
+ Global Name
+
+
+ ECMAScript Language Association
+
+
+
%AggregateError%
@@ -3285,7 +3457,7 @@ Well-Known Intrinsic Objects
- The prototype of Array iterator objects (
@@ -3295,7 +3467,7 @@ Well-Known Intrinsic Objects
- The prototype of async-from-sync iterator objects (
@@ -3503,6 +3675,17 @@ Well-Known Intrinsic Objects
The FinalizationRegistry constructor (
+
+
+ %Float16Array%
+
+
+ `Float16Array`
+
+
+ The Float16Array constructor (
+
%Float32Array%
@@ -3532,7 +3715,7 @@ Well-Known Intrinsic Objects
- The prototype of For-In iterator objects (
@@ -3623,12 +3806,23 @@ Well-Known Intrinsic Objects
- %IteratorPrototype%
+ %Iterator%
+ `Iterator`
- An object that all standard built-in iterator objects indirectly inherit from
+ The `Iterator` constructor (
+
+
+
+ %IteratorHelperPrototype%
+
+
+
+
+ The prototype of Iterator Helper objects (
@@ -3660,7 +3854,7 @@ Well-Known Intrinsic Objects
- The prototype of Map iterator objects (
@@ -3812,7 +4006,7 @@ Well-Known Intrinsic Objects
- The prototype of Set iterator objects (
@@ -3844,7 +4038,7 @@ Well-Known Intrinsic Objects
- The prototype of String iterator objects (
@@ -3988,6 +4182,16 @@ Well-Known Intrinsic Objects
The WeakSet constructor (
+
+
+ %WrapForValidIteratorPrototype%
+
+
+
+
+ The prototype of wrapped iterator objects returned by Iterator.from (
+
@@ -3999,11 +4203,11 @@ Well-Known Intrinsic Objects
ECMAScript Specification Types
- A specification type corresponds to meta-values that are used within algorithms to describe the semantics of ECMAScript language constructs and ECMAScript language types. The specification types include Reference, List, Completion Record, Property Descriptor, Environment Record, Abstract Closure, and Data Block. Specification type values are specification artefacts that do not necessarily correspond to any specific entity within an ECMAScript implementation. Specification type values may be used to describe intermediate results of ECMAScript expression evaluation but such values cannot be stored as properties of objects or values of ECMAScript language variables.
+ A specification type corresponds to meta-values that are used within algorithms to describe the semantics of ECMAScript language constructs and ECMAScript language types. The specification types include Reference Record, List, Completion Record, Property Descriptor, Environment Record, Abstract Closure, and Data Block. Specification type values are specification artefacts that do not necessarily correspond to any specific entity within an ECMAScript implementation. Specification type values may be used to describe intermediate results of ECMAScript expression evaluation but such values cannot be stored as properties of objects or values of ECMAScript language variables.
The Enum Specification Type
- Enums are values which are internal to the specification and not directly observable from ECMAScript code. Enums are denoted using a ~sans-serif~ typeface. For instance, a Completion Record's [[Type]] field takes on values like ~normal~, ~return~, or ~throw~. Enums have no characteristics other than their name. The name of an enum serves no purpose other than to distinguish it from other enums, and implies nothing about its usage or meaning in context.
+ Enums are values which are internal to the specification and not directly observable from ECMAScript code. Enums are denoted in upper kebab case using a ~sans-serif~ typeface. For instance, a Completion Record's [[Type]] field takes on values like ~normal~, ~return~, or ~throw~. Enums have no characteristics other than their name. The name of an enum serves no purpose other than to distinguish it from other enums, and implies nothing about its usage or meaning in context.
@@ -4022,7 +4226,7 @@ The List and Record Specification Types
The Set and Relation Specification Types
The Set type is used to explain a collection of unordered elements for use in the memory model. It is distinct from the ECMAScript collection type of the same name. To disambiguate, instances of the ECMAScript collection are consistently referred to as "Set objects" within this specification. Values of the Set type are simple collections of elements, where no element appears more than once. Elements may be added to and removed from Sets. Sets may be unioned, intersected, or subtracted from each other.
- The Relation type is used to explain constraints on Sets. Values of the Relation type are Sets of ordered pairs of values from its value domain. For example, a Relation on events is a set of ordered pairs of events. For a Relation _R_ and two values _a_ and _b_ in the value domain of _R_, _a_ _R_ _b_ is shorthand for saying the ordered pair (_a_, _b_) is a member of _R_. A Relation is the least Relation with respect to some conditions when it is the smallest Relation that satisfies those conditions.
+ The Relation type is used to explain constraints on Sets. Values of the Relation type are Sets of ordered pairs of values from its value domain. For example, a Relation on Memory events is a set of ordered pairs of Memory events. For a Relation _R_ and two values _a_ and _b_ in the value domain of _R_, _a_ _R_ _b_ is shorthand for saying the ordered pair (_a_, _b_) is a member of _R_. A Relation is the least Relation with respect to some conditions when it is the smallest Relation that satisfies those conditions.
A strict partial order is a Relation value _R_ that satisfies the following.
-
@@ -4058,17 +4262,19 @@
The Completion Record Specification Type
Completion Records have the fields defined in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Type]]
@@ -4124,6 +4330,8 @@
): a normal completion
+ - skip return checks
+ - true
1. Return Completion Record { [[Type]]: ~normal~, [[Value]]: _value_, [[Target]]: ~empty~ }.
@@ -4143,6 +4351,19 @@
+
+
+ ReturnCompletion (
+ _value_: an ECMAScript language value,
+ ): a return completion
+
+
+
+
+ 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _value_, [[Target]]: ~empty~ }.
+
+
+
UpdateEmpty (
@@ -4163,15 +4384,17 @@
The Reference Record Specification Type
The Reference Record type is used to explain the behaviour of such operators as `delete`, `typeof`, the assignment operators, the `super` keyword and other language features. For example, the left-hand operand of an assignment is expected to produce a Reference Record.
- A Reference Record is a resolved name or property binding; its fields are defined by
+ A Reference Record is a resolved name or (possibly not-yet-resolved) property binding; its fields are defined by
-
- Field Name
- Value
- Meaning
-
+
+
+ Field Name
+ Value
+ Meaning
+
+
[[Base]]
an ECMAScript language value, an Environment Record, or ~unresolvable~
@@ -4179,8 +4402,8 @@ The Reference Record Specification Type
[[ReferencedName]]
- a String, a Symbol, or a Private Name
- The name of the binding. Always a String if [[Base]] value is an Environment Record.
+ an ECMAScript language value or a Private Name
+ The name of the binding. Always a String if [[Base]] value is an Environment Record. Otherwise, may be an ECMAScript language value other than a String or a Symbol until ToPropertyKey is performed.
[[Strict]]
@@ -4207,7 +4430,8 @@
1. If _V_.[[Base]] is ~unresolvable~, return *false*.
- 1. If _V_.[[Base]] is an Environment Record, return *false*; otherwise return *true*.
+ 1. If _V_.[[Base]] is an Environment Record, return *false*.
+ 1. Return *true*.
@@ -4220,7 +4444,8 @@
- 1. If _V_.[[Base]] is ~unresolvable~, return *true*; otherwise return *false*.
+ 1. If _V_.[[Base]] is ~unresolvable~, return *true*.
+ 1. Return *false*.
@@ -4233,7 +4458,8 @@
- 1. If _V_.[[ThisValue]] is not ~empty~, return *true*; otherwise return *false*.
+ 1. If _V_.[[ThisValue]] is ~empty~, return *false*.
+ 1. Return *true*.
@@ -4246,7 +4472,8 @@
- 1. If _V_.[[ReferencedName]] is a Private Name, return *true*; otherwise return *false*.
+ 1. If _V_.[[ReferencedName]] is a Private Name, return *true*.
+ 1. Return *false*.
@@ -4265,11 +4492,12 @@
1. [id="step-getvalue-toobject"] Let _baseObj_ be ? ToObject(_V_.[[Base]]).
1. If IsPrivateReference(_V_) is *true*, then
1. Return ? PrivateGet(_baseObj_, _V_.[[ReferencedName]]).
- 1. Return ? _baseObj_.[[Get]] (_V_.[[ReferencedName]], GetThisValue(_V_)).
- 1. Else,
- 1. Let _base_ be _V_.[[Base]].
- 1. Assert: _base_ is an Environment Record.
- 1. Return ? _base_.GetBindingValue (_V_.[[ReferencedName]], _V_.[[Strict]]) (see _baseObj_.[[Get]](_V_.[[ReferencedName]], GetThisValue(_V_)) .
+ 1. Let _base_ be _V_.[[Base]].
+ 1. Assert: _base_ is an Environment Record.
+ 1. Return ? _base_.GetBindingValue(_V_.[[ReferencedName]], _V_.[[Strict]]) (see
The object that may be created in step
@@ -4296,13 +4524,14 @@
1. [id="step-putvalue-toobject"] Let _baseObj_ be ? ToObject(_V_.[[Base]]).
1. If IsPrivateReference(_V_) is *true*, then
1. Return ? PrivateSet(_baseObj_, _V_.[[ReferencedName]], _W_).
- 1. Let _succeeded_ be ? _baseObj_.[[Set]] (_V_.[[ReferencedName]], _W_, GetThisValue(_V_)).
+ 1. If _V_.[[ReferencedName]] is not a property key, then
+ 1. Set _V_.[[ReferencedName]] to ? ToPropertyKey(_V_.[[ReferencedName]]).
+ 1. Let _succeeded_ be ? _baseObj_.[[Set]](_V_.[[ReferencedName]], _W_, GetThisValue(_V_)) .
1. If _succeeded_ is *false* and _V_.[[Strict]] is *true*, throw a *TypeError* exception.
1. Return ~unused~.
- 1. Else,
- 1. Let _base_ be _V_.[[Base]].
- 1. Assert: _base_ is an Environment Record.
- 1. Return ? _base_.SetMutableBinding (_V_.[[ReferencedName]], _W_, _V_.[[Strict]]) (see _base_.SetMutableBinding(_V_.[[ReferencedName]], _W_, _V_.[[Strict]]) (see
The object that may be created in step
@@ -4319,7 +4548,8 @@
1. Assert: IsPropertyReference(_V_) is *true*.
- 1. If IsSuperReference(_V_) is *true*, return _V_.[[ThisValue]]; otherwise return _V_.[[Base]].
+ 1. If IsSuperReference(_V_) is *true*, return _V_.[[ThisValue]].
+ 1. Return _V_.[[Base]].
@@ -4350,9 +4580,9 @@
- 1. Let _privEnv_ be the running execution context's PrivateEnvironment.
- 1. Assert: _privEnv_ is not *null*.
- 1. Let _privateName_ be ResolvePrivateIdentifier(_privEnv_, _privateIdentifier_).
+ 1. Let _privateEnv_ be the running execution context's PrivateEnvironment.
+ 1. Assert: _privateEnv_ is not *null*.
+ 1. Let _privateName_ be ResolvePrivateIdentifier(_privateEnv_, _privateIdentifier_).
1. Return the Reference Record { [[Base]]: _baseValue_, [[ReferencedName]]: _privateName_, [[Strict]]: *true*, [[ThisValue]]: ~empty~ }.
@@ -4367,13 +4597,12 @@ The Property Descriptor Specification Type
IsAccessorDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _Desc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
1. If _Desc_ has a [[Get]] field, return *true*.
1. If _Desc_ has a [[Set]] field, return *true*.
1. Return *false*.
@@ -4383,13 +4612,12 @@
IsDataDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _Desc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
1. If _Desc_ has a [[Value]] field, return *true*.
1. If _Desc_ has a [[Writable]] field, return *true*.
1. Return *false*.
@@ -4399,13 +4627,12 @@
IsGenericDescriptor (
- _Desc_: a Property Descriptor or *undefined*,
+ _Desc_: a Property Descriptor,
): a Boolean
- 1. If _Desc_ is *undefined*, return *false*.
1. If IsAccessorDescriptor(_Desc_) is *true*, return *false*.
1. If IsDataDescriptor(_Desc_) is *true*, return *false*.
1. Return *true*.
@@ -4529,10 +4756,10 @@ The Abstract Closure Specification Type
Data Blocks
The Data Block specification type is used to describe a distinct and mutable sequence of byte-sized (8 bit) numeric values. A byte value is an integer in the inclusive interval from 0 to 255. A Data Block value is created with a fixed number of bytes that each have the initial value 0.
- For notational convenience within this specification, an array-like syntax can be used to access the individual bytes of a Data Block value. This notation presents a Data Block value as a 0-origined integer-indexed sequence of bytes. For example, if _db_ is a 5 byte Data Block value then _db_[2] can be used to access its 3rd byte.
+ For notational convenience within this specification, an array-like syntax can be used to access the individual bytes of a Data Block value. This notation presents a Data Block value as a 0-based integer-indexed sequence of bytes. For example, if _db_ is a 5 byte Data Block value then _db_[2] can be used to access its 3rd byte.
A data block that resides in memory that can be referenced from multiple agents concurrently is designated a Shared Data Block. A Shared Data Block has an identity (for the purposes of equality testing Shared Data Block values) that is address-free: it is tied not to the virtual addresses the block is mapped to in any process, but to the set of locations in memory that the block represents. Two data blocks are equal only if the sets of the locations they contain are equal; otherwise, they are not equal and the intersection of the sets of locations they contain is empty. Finally, Shared Data Blocks can be distinguished from Data Blocks.
The semantics of Shared Data Blocks is defined using Shared Data Block events by the memory model. Abstract operations below introduce Shared Data Block events and act as the interface between evaluation semantics and the event semantics of the memory model. The events form a candidate execution, on which the memory model acts as a filter. Please consult the memory model for full semantics.
- Shared Data Block events are modeled by Records, defined in the memory model.
+ Shared Data Block events are modelled by Records, defined in the memory model.
The following abstract operations are used in this specification to operate upon Data Block values:
@@ -4561,7 +4788,8 @@
1. Let _db_ be a new Shared Data Block value consisting of _size_ bytes. If it is impossible to create such a Shared Data Block, throw a *RangeError* exception.
- 1. Let _execution_ be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
+ 1. Let _AR_ be the Agent Record of the surrounding agent.
+ 1. Let _execution_ be _AR_.[[CandidateExecution]].
1. Let _eventsRecord_ be the Agent Events Record of _execution_.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
1. Let _zero_ be « 0 ».
1. For each index _i_ of _db_, do
@@ -4590,7 +4818,8 @@
1. Assert: _toIndex_ + _count_ ≤ _toSize_.
1. Repeat, while _count_ > 0,
1. If _fromBlock_ is a Shared Data Block, then
- 1. Let _execution_ be the [[CandidateExecution]] field of the surrounding agent's Agent Record.
+ 1. Let _AR_ be the Agent Record of the surrounding agent.
+ 1. Let _execution_ be _AR_.[[CandidateExecution]].
1. Let _eventsRecord_ be the Agent Events Record of _execution_.[[EventsRecords]] whose [[AgentSignifier]] is AgentSignifier().
1. Let _bytes_ be a List whose sole element is a nondeterministically chosen byte value.
1. NOTE: In implementations, _bytes_ is the result of a non-atomic read instruction on the underlying hardware. The nondeterminism is a semantic prescription of the memory model to describe observable behaviour of hardware with weak consistency.
@@ -4618,20 +4847,22 @@ The PrivateElement Specification Type
Values of the PrivateElement type are Record values whose fields are defined by
-
-
- Field Name
-
-
- Values of the [[Kind]] field for which it is present
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Values of the [[Kind]] field for which it is present
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Key]]
@@ -4712,17 +4943,19 @@ The ClassFieldDefinition Record Specification Type
Values of the ClassFieldDefinition type are Record values whose fields are defined by
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Name]]
@@ -4751,7 +4984,7 @@ The ClassFieldDefinition Record Specification Type
Private Names
- The Private Name specification type is used to describe a globally unique value (one which differs from any other Private Name, even if they are otherwise indistinguishable) which represents the key of a private class element (field, method, or accessor). Each Private Name has an associated immutable [[Description]] which is a String value. A Private Name may be installed on any ECMAScript object with PrivateFieldAdd or PrivateMethodOrAccessorAdd, and then read or written using PrivateGet and PrivateSet.
+ The Private Name specification type is used to describe a globally unique value (one which differs from any other Private Name, even if they are otherwise indistinguishable) which represents the key of a private class element (field, method, or accessor). Each Private Name has an immutable [[Description]] internal slot which is a String. A Private Name may be installed on any ECMAScript object with PrivateFieldAdd or PrivateMethodOrAccessorAdd, and then read or written using PrivateGet and PrivateSet.
@@ -4760,17 +4993,19 @@ The ClassStaticBlockDefinition Record Specification Type
ClassStaticBlockDefinition Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[BodyFunction]]
@@ -4810,7 +5045,7 @@
1. If _input_ is an Object, then
- 1. Let _exoticToPrim_ be ? GetMethod(_input_, @@toPrimitive).
+ 1. Let _exoticToPrim_ be ? GetMethod(_input_, %Symbol.toPrimitive%).
1. If _exoticToPrim_ is not *undefined*, then
1. If _preferredType_ is not present, then
1. Let _hint_ be *"default"*.
@@ -4822,12 +5057,12 @@
1. Let _result_ be ? Call(_exoticToPrim_, _input_, « _hint_ »).
1. If _result_ is not an Object, return _result_.
1. Throw a *TypeError* exception.
- 1. If _preferredType_ is not present, let _preferredType_ be ~number~.
+ 1. If _preferredType_ is not present, set _preferredType_ to ~number~.
1. Return ? OrdinaryToPrimitive(_input_, _preferredType_).
1. Return _input_.
- When ToPrimitive is called without a hint, then it generally behaves as if the hint were ~number~. However, objects may over-ride this behaviour by defining a @@toPrimitive method. Of the objects defined in this specification only Dates (see
+ When ToPrimitive is called without a hint, then it generally behaves as if the hint were ~number~. However, objects may over-ride this behaviour by defining a %Symbol.toPrimitive% method. Of the objects defined in this specification only Dates (see
@@ -4854,7 +5089,7 @@
-
+
ToBoolean (
_argument_: an ECMAScript language value,
@@ -4867,7 +5102,8 @@
1. If _argument_ is a Boolean, return _argument_.
1. If _argument_ is one of *undefined*, *null*, *+0*𝔽, *-0*𝔽, *NaN*, *0*ℤ, or the empty String, return *false*.
- 1. [id="step-to-boolean-web-compat-insertion-point"] NOTE: This step is replaced in section
@@ -5024,20 +5260,20 @@ Runtime Semantics: StringNumericValue ( ): a Number
1. Else,
1. Let _b_ be 0.
1. Let _n_ be 0.
- 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|. Otherwise, let _e_ be 0.
+ 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|; else let _e_ be 0.
1. Return RoundMVResult((_a_ + (_b_ × 10-_n_)) × 10_e_).
StrUnsignedDecimalLiteral ::: `.` DecimalDigits ExponentPart?
1. Let _b_ be the MV of |DecimalDigits|.
- 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|. Otherwise, let _e_ be 0.
+ 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|; else let _e_ be 0.
1. Let _n_ be the number of code points in |DecimalDigits|.
1. Return RoundMVResult(_b_ × 10_e_ - _n_).
StrUnsignedDecimalLiteral ::: DecimalDigits ExponentPart?
1. Let _a_ be the MV of |DecimalDigits|.
- 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|. Otherwise, let _e_ be 0.
+ 1. If |ExponentPart| is present, let _e_ be the MV of |ExponentPart|; else let _e_ be 0.
1. Return RoundMVResult(_a_ × 10_e_).
@@ -5100,7 +5336,8 @@
1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
1. Let _int_ be truncate(ℝ(_number_)).
1. Let _int32bit_ be _int_ modulo 232.
- 1. If _int32bit_ ≥ 231, return 𝔽(_int32bit_ - 232); otherwise return 𝔽(_int32bit_).
+ 1. If _int32bit_ ≥ 231, return 𝔽(_int32bit_ - 232).
+ 1. Return 𝔽(_int32bit_).
Given the above definition of ToInt32:
@@ -5169,7 +5406,8 @@
1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
1. Let _int_ be truncate(ℝ(_number_)).
1. Let _int16bit_ be _int_ modulo 216.
- 1. If _int16bit_ ≥ 215, return 𝔽(_int16bit_ - 216); otherwise return 𝔽(_int16bit_).
+ 1. If _int16bit_ ≥ 215, return 𝔽(_int16bit_ - 216).
+ 1. Return 𝔽(_int16bit_).
@@ -5218,7 +5456,8 @@
1. If _number_ is not finite or _number_ is either *+0*𝔽 or *-0*𝔽, return *+0*𝔽.
1. Let _int_ be truncate(ℝ(_number_)).
1. Let _int8bit_ be _int_ modulo 28.
- 1. If _int8bit_ ≥ 27, return 𝔽(_int8bit_ - 28); otherwise return 𝔽(_int8bit_).
+ 1. If _int8bit_ ≥ 27, return 𝔽(_int8bit_ - 28).
+ 1. Return 𝔽(_int8bit_).
@@ -5259,7 +5498,8 @@
1. Let _f_ be floor(_clamped_).
1. If _clamped_ < _f_ + 0.5, return 𝔽(_f_).
1. If _clamped_ > _f_ + 0.5, return 𝔽(_f_ + 1).
- 1. If _f_ is even, return 𝔽(_f_). Otherwise, return 𝔽(_f_ + 1).
+ 1. If _f_ is even, return 𝔽(_f_).
+ 1. Return 𝔽(_f_ + 1).
Unlike most other ECMAScript integer conversion operations, ToUint8Clamp rounds rather than truncates non-integral values. It also uses “round half to even” tie-breaking, which differs from the “round half up” tie-breaking of `Math.round` .
@@ -5282,14 +5522,16 @@
-
-
- Argument Type
-
-
- Result
-
-
+
+
+
+ Argument Type
+
+
+ Result
+
+
+
Undefined
@@ -5411,7 +5653,8 @@
1. Let _n_ be ? ToBigInt(_argument_).
1. Let _int64bit_ be ℝ(_n_) modulo 264.
- 1. If _int64bit_ ≥ 263, return ℤ(_int64bit_ - 264); otherwise return ℤ(_int64bit_).
+ 1. If _int64bit_ ≥ 263, return ℤ(_int64bit_ - 264).
+ 1. Return ℤ(_int64bit_).
@@ -5458,7 +5701,7 @@
-
+
ToObject (
_argument_: an ECMAScript language value,
@@ -5466,84 +5709,18 @@
- description
- - It converts _argument_ to a value of type Object according to
+ - It converts _argument_ to a value of type Object.
-
-
-
-
- Argument Type
-
-
- Result
-
-
-
-
- Undefined
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Null
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Boolean
-
-
- Return a new Boolean object whose [[BooleanData]] internal slot is set to _argument_. See
-
-
-
- Number
-
-
- Return a new Number object whose [[NumberData]] internal slot is set to _argument_. See
-
-
-
- String
-
-
- Return a new String object whose [[StringData]] internal slot is set to _argument_. See
-
-
-
- Symbol
-
-
- Return a new Symbol object whose [[SymbolData]] internal slot is set to _argument_. See
-
-
-
- BigInt
-
-
- Return a new BigInt object whose [[BigIntData]] internal slot is set to _argument_. See
-
-
-
- Object
-
-
- Return _argument_.
-
-
-
-
+
+ 1. If _argument_ is either *undefined* or *null*, throw a *TypeError* exception.
+ 1. If _argument_ is a Boolean, return a new Boolean object whose [[BooleanData]] internal slot is set to _argument_. See
@@ -5568,11 +5745,11 @@
ToLength (
_argument_: an ECMAScript language value,
- ): either a normal completion containing an integral Number or a throw completion
+ ): either a normal completion containing a non-negative integral Number or a throw completion
- description
- - It clamps and truncates _argument_ to an integral Number suitable for use as the length of an array-like object.
+ - It clamps and truncates _argument_ to a non-negative integral Number suitable for use as the length of an array-like object.
1. Let _len_ be ? ToIntegerOrInfinity(_argument_).
@@ -5589,7 +5766,7 @@
- description
- - If _argument_ is either *"-0"* or exactly matches the result of ToString(_n_) for some Number value _n_, it returns the respective Number value. Otherwise, it returns *undefined*.
+ - If _argument_ is either *"-0"* or exactly matches ToString(_n_) for some Number value _n_, it returns the respective Number value. Otherwise, it returns *undefined*.
1. If _argument_ is *"-0"*, return *-0*𝔽.
@@ -5597,7 +5774,7 @@
1. If ! ToString(_n_) is _argument_, return _n_.
1. Return *undefined*.
- A canonical numeric string is any String value for which the CanonicalNumericIndexString abstract operation does not return *undefined*.
+ A canonical numeric string is any String for which the CanonicalNumericIndexString abstract operation does not return *undefined*.
@@ -5621,92 +5798,20 @@
Testing and Comparison Operations
-
+
RequireObjectCoercible (
_argument_: an ECMAScript language value,
- ): either a normal completion containing an ECMAScript language value or a throw completion
+ ): either a normal completion containing ~unused~ or a throw completion
- description
- - It throws an error if _argument_ is a value that cannot be converted to an Object using ToObject. It is defined by
+ - It throws an error if _argument_ is a value that cannot be converted to an Object using ToObject.
-
-
-
-
- Argument Type
-
-
- Result
-
-
-
-
- Undefined
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Null
-
-
- Throw a *TypeError* exception.
-
-
-
-
- Boolean
-
-
- Return _argument_.
-
-
-
-
- Number
-
-
- Return _argument_.
-
-
-
-
- String
-
-
- Return _argument_.
-
-
-
-
- Symbol
-
-
- Return _argument_.
-
-
-
-
- BigInt
-
-
- Return _argument_.
-
-
-
-
- Object
-
-
- Return _argument_.
-
-
-
-
+
+ 1. If _argument_ is either *undefined* or *null*, throw a *TypeError* exception.
+ 1. Return ~unused~.
+
@@ -5773,25 +5878,7 @@
- It is used to determine whether additional properties can be added to _O_.
- 1. Return ? _O_.[[IsExtensible]] ().
-
-
-
-
-
- IsIntegralNumber (
- _argument_: an ECMAScript language value,
- ): a Boolean
-
-
- - description
- - It determines if _argument_ is a finite integral Number value.
-
-
- 1. If _argument_ is not a Number, return *false*.
- 1. If _argument_ is not finite, return *false*.
- 1. If truncate(ℝ(_argument_)) ≠ ℝ(_argument_), return *false*.
- 1. Return *true*.
+ 1. Return ? _O_.[[IsExtensible]]() .
@@ -5805,7 +5892,7 @@
1. If _argument_ is not an Object, return *false*.
- 1. Let _matcher_ be ? Get(_argument_, @@match).
+ 1. Let _matcher_ be ? Get(_argument_, %Symbol.match%).
1. If _matcher_ is not *undefined*, return ToBoolean(_matcher_).
1. If _argument_ has a [[RegExpMatcher]] internal slot, return *true*.
1. Return *false*.
@@ -5833,6 +5920,30 @@
+
+
+ SameType (
+ _x_: an ECMAScript language value,
+ _y_: an ECMAScript language value,
+ ): a Boolean
+
+
+ - description
+ - It determines whether or not the two arguments are the same type.
+
+
+ 1. If _x_ is *undefined* and _y_ is *undefined*, return *true*.
+ 1. If _x_ is *null* and _y_ is *null*, return *true*.
+ 1. If _x_ is a Boolean and _y_ is a Boolean, return *true*.
+ 1. If _x_ is a Number and _y_ is a Number, return *true*.
+ 1. If _x_ is a BigInt and _y_ is a BigInt, return *true*.
+ 1. If _x_ is a Symbol and _y_ is a Symbol, return *true*.
+ 1. If _x_ is a String and _y_ is a String, return *true*.
+ 1. If _x_ is an Object and _y_ is an Object, return *true*.
+ 1. Return *false*.
+
+
+
SameValue (
@@ -5845,7 +5956,7 @@
- It determines whether or not the two arguments are the same value.
- 1. If Type(_x_) is not Type(_y_), return *false*.
+ 1. If SameType(_x_, _y_) is *false*, return *false*.
1. If _x_ is a Number, then
1. Return Number::sameValue(_x_, _y_).
1. Return SameValueNonNumber(_x_, _y_).
@@ -5867,7 +5978,7 @@
- It determines whether or not the two arguments are the same value (ignoring the difference between *+0*𝔽 and *-0*𝔽).
- 1. If Type(_x_) is not Type(_y_), return *false*.
+ 1. If SameType(_x_, _y_) is *false*, return *false*.
1. If _x_ is a Number, then
1. Return Number::sameValueZero(_x_, _y_).
1. Return SameValueNonNumber(_x_, _y_).
@@ -5887,16 +5998,19 @@
- 1. Assert: Type(_x_) is Type(_y_).
- 1. If _x_ is either *null* or *undefined*, return *true*.
+ 1. Assert: SameType(_x_, _y_) is *true*.
+ 1. If _x_ is either *undefined* or *null*, return *true*.
1. If _x_ is a BigInt, then
1. Return BigInt::equal(_x_, _y_).
1. If _x_ is a String, then
- 1. If _x_ and _y_ have the same length and the same code units in the same positions, return *true*; otherwise, return *false*.
+ 1. If _x_ and _y_ have the same length and the same code units in the same positions, return *true*.
+ 1. Return *false*.
1. If _x_ is a Boolean, then
- 1. If _x_ and _y_ are both *true* or both *false*, return *true*; otherwise, return *false*.
+ 1. If _x_ and _y_ are both *true* or both *false*, return *true*.
+ 1. Return *false*.
1. NOTE: All other ECMAScript language values are compared by identity.
- 1. If _x_ is _y_, return *true*; otherwise, return *false*.
+ 1. If _x_ is _y_, return *true*.
+ 1. Return *false*.
For expository purposes, some cases are handled separately within this algorithm even if it is unnecessary to do so.
@@ -5934,30 +6048,29 @@
1. Let _cy_ be the numeric value of the code unit at index _i_ within _py_.
1. If _cx_ < _cy_, return *true*.
1. If _cx_ > _cy_, return *false*.
- 1. If _lx_ < _ly_, return *true*. Otherwise, return *false*.
- 1. Else,
- 1. If _px_ is a BigInt and _py_ is a String, then
- 1. Let _ny_ be StringToBigInt(_py_).
- 1. If _ny_ is *undefined*, return *undefined*.
- 1. Return BigInt::lessThan(_px_, _ny_).
- 1. If _px_ is a String and _py_ is a BigInt, then
- 1. Let _nx_ be StringToBigInt(_px_).
- 1. If _nx_ is *undefined*, return *undefined*.
- 1. Return BigInt::lessThan(_nx_, _py_).
- 1. NOTE: Because _px_ and _py_ are primitive values, evaluation order is not important.
- 1. Let _nx_ be ? ToNumeric(_px_) .
- 1. Let _ny_ be ? ToNumeric(_py_) .
- 1. If Type(_nx_) is Type(_ny_), then
- 1. If _nx_ is a Number, then
- 1. Return Number::lessThan(_nx_, _ny_).
- 1. Else,
- 1. Assert: _nx_ is a BigInt.
- 1. Return BigInt::lessThan(_nx_, _ny_).
- 1. Assert: _nx_ is a BigInt and _ny_ is a Number, or _nx_ is a Number and _ny_ is a BigInt.
- 1. If _nx_ or _ny_ is *NaN*, return *undefined*.
- 1. If _nx_ is *-∞*𝔽 or _ny_ is *+∞*𝔽, return *true*.
- 1. If _nx_ is *+∞*𝔽 or _ny_ is *-∞*𝔽, return *false*.
- 1. If ℝ(_nx_) < ℝ(_ny_), return *true*; otherwise return *false*.
+ 1. If _lx_ < _ly_, return *true*.
+ 1. Return *false*.
+ 1. If _px_ is a BigInt and _py_ is a String, then
+ 1. Let _ny_ be StringToBigInt(_py_).
+ 1. If _ny_ is *undefined*, return *undefined*.
+ 1. Return BigInt::lessThan(_px_, _ny_).
+ 1. If _px_ is a String and _py_ is a BigInt, then
+ 1. Let _nx_ be StringToBigInt(_px_).
+ 1. If _nx_ is *undefined*, return *undefined*.
+ 1. Return BigInt::lessThan(_nx_, _py_).
+ 1. NOTE: Because _px_ and _py_ are primitive values, evaluation order is not important.
+ 1. Let _nx_ be ? ToNumeric(_px_) .
+ 1. Let _ny_ be ? ToNumeric(_py_) .
+ 1. If SameType(_nx_, _ny_) is *true*, then
+ 1. If _nx_ is a Number, return Number::lessThan(_nx_, _ny_).
+ 1. Assert: _nx_ is a BigInt.
+ 1. Return BigInt::lessThan(_nx_, _ny_).
+ 1. Assert: _nx_ is a BigInt and _ny_ is a Number, or _nx_ is a Number and _ny_ is a BigInt.
+ 1. If _nx_ or _ny_ is *NaN*, return *undefined*.
+ 1. If _nx_ is *-∞*𝔽 or _ny_ is *+∞*𝔽, return *true*.
+ 1. If _nx_ is *+∞*𝔽 or _ny_ is *-∞*𝔽, return *false*.
+ 1. If ℝ(_nx_) < ℝ(_ny_), return *true*.
+ 1. Return *false*.
Step
@@ -5967,7 +6080,7 @@
-
+
IsLooselyEqual (
_x_: an ECMAScript language value,
@@ -5979,11 +6092,13 @@
- It provides the semantics for the `==` operator.
- 1. If Type(_x_) is Type(_y_), then
+ 1. If SameType(_x_, _y_) is *true*, then
1. Return IsStrictlyEqual(_x_, _y_).
1. If _x_ is *null* and _y_ is *undefined*, return *true*.
1. If _x_ is *undefined* and _y_ is *null*, return *true*.
- 1. [id="step-abstract-equality-comparison-web-compat-insertion-point"] NOTE: This step is replaced in section
1. If _x_ is an Object and _y_ is either a String, a Number, a BigInt, or a Symbol, return ! IsLooselyEqual(? ToPrimitive(_x_), _y_).
1. If _x_ is a BigInt and _y_ is a Number, or if _x_ is a Number and _y_ is a BigInt, then
1. If _x_ is not finite or _y_ is not finite, return *false*.
- 1. If ℝ(_x_) = ℝ(_y_), return *true*; otherwise return *false*.
+ 1. If ℝ(_x_) = ℝ(_y_), return *true*.
+ 1. Return *false*.
1. Return *false*.
@@ -6014,7 +6130,7 @@
- It provides the semantics for the `===` operator.
- 1. If Type(_x_) is not Type(_y_), return *false*.
+ 1. If SameType(_x_, _y_) is *false*, return *false*.
1. If _x_ is a Number, then
1. Return Number::equal(_x_, _y_).
1. Return SameValueNonNumber(_x_, _y_).
@@ -6040,7 +6156,10 @@
+ 1. Set _internalSlotsList_ to the list-concatenation of _internalSlotsList_ and « [[PrivateElements]] ».
1. Let _obj_ be a newly created object with an internal slot for each name in _internalSlotsList_.
+ 1. NOTE: As described in
- It is used to retrieve the value of a specific property of an object.
- 1. Return ? _O_.[[Get]] (_P_, _O_).
+ 1. Return ? _O_.[[Get]](_P_, _O_) .
@@ -6082,7 +6201,7 @@
1. Let _O_ be ? ToObject(_V_).
- 1. Return ? _O_.[[Get]] (_P_, _V_).
+ 1. Return ? _O_.[[Get]](_P_, _V_) .
@@ -6100,7 +6219,7 @@
- It is used to set the value of a specific property of an object. _V_ is the new value for the property.
- 1. Let _success_ be ? _O_.[[Set]] (_P_, _V_, _O_).
+ 1. Let _success_ be ? _O_.[[Set]](_P_, _V_, _O_) .
1. If _success_ is *false* and _Throw_ is *true*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -6120,7 +6239,7 @@
1. Let _newDesc_ be the PropertyDescriptor { [[Value]]: _V_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
- 1. Return ? _O_.[[DefineOwnProperty]] (_P_, _newDesc_).
+ 1. Return ? _O_.[[DefineOwnProperty]](_P_, _newDesc_) .
This abstract operation creates a property whose attributes are set to the same defaults used for properties created by the ECMAScript language assignment operator. Normally, the property will not already exist. If it does exist and is not configurable or if _O_ is not extensible, [[DefineOwnProperty]] will return *false*.
@@ -6185,7 +6304,7 @@
- It is used to call the [[DefineOwnProperty]] internal method of an object in a manner that will throw a *TypeError* exception if the requested property update cannot be performed.
- 1. Let _success_ be ? _O_.[[DefineOwnProperty]] (_P_, _desc_).
+ 1. Let _success_ be ? _O_.[[DefineOwnProperty]](_P_, _desc_) .
1. If _success_ is *false*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -6203,7 +6322,7 @@
- It is used to remove a specific own property of an object. It throws an exception if the property is not configurable.
- 1. Let _success_ be ? _O_.[[Delete]] (_P_).
+ 1. Let _success_ be ? _O_.[[Delete]](_P_) .
1. If _success_ is *false*, throw a *TypeError* exception.
1. Return ~unused~.
@@ -6240,7 +6359,7 @@
- It is used to determine whether an object has a property with the specified property key. The property may be either own or inherited.
- 1. Return ? _O_.[[HasProperty]] (_P_).
+ 1. Return ? _O_.[[HasProperty]](_P_) .
@@ -6256,7 +6375,7 @@
- It is used to determine whether an object has an own property with the specified property key.
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_P_).
+ 1. Let _desc_ be ? _O_.[[GetOwnProperty]](_P_) .
1. If _desc_ is *undefined*, return *false*.
1. Return *true*.
@@ -6277,7 +6396,7 @@
1. If _argumentsList_ is not present, set _argumentsList_ to a new empty List.
1. If IsCallable(_F_) is *false*, throw a *TypeError* exception.
- 1. Return ? _F_.[[Call]] (_V_, _argumentsList_).
+ 1. Return ? _F_.[[Call]](_V_, _argumentsList_) .
@@ -6296,7 +6415,7 @@
1. If _newTarget_ is not present, set _newTarget_ to _F_.
1. If _argumentsList_ is not present, set _argumentsList_ to a new empty List.
- 1. Return ? _F_.[[Construct]] (_argumentsList_, _newTarget_).
+ 1. Return ? _F_.[[Construct]](_argumentsList_, _newTarget_) .
If _newTarget_ is not present, this operation is equivalent to: `new F(...argumentsList)`
@@ -6324,7 +6443,7 @@
1. Else,
1. Assert: _level_ is ~frozen~.
1. For each element _k_ of _keys_, do
- 1. Let _currentDesc_ be ? _O_.[[GetOwnProperty]] (_k_).
+ 1. Let _currentDesc_ be ? _O_.[[GetOwnProperty]](_k_) .
1. If _currentDesc_ is not *undefined*, then
1. If IsAccessorDescriptor(_currentDesc_) is *true*, then
1. Let _desc_ be the PropertyDescriptor { [[Configurable]]: *false* }.
@@ -6352,7 +6471,7 @@
1. NOTE: If the object is extensible, none of its properties are examined.
1. Let _keys_ be ? _O_.[[OwnPropertyKeys]]().
1. For each element _k_ of _keys_, do
- 1. Let _currentDesc_ be ? _O_.[[GetOwnProperty]] (_k_).
+ 1. Let _currentDesc_ be ? _O_.[[GetOwnProperty]](_k_) .
1. If _currentDesc_ is not *undefined*, then
1. If _currentDesc_.[[Configurable]] is *true*, return *false*.
1. If _level_ is ~frozen~ and IsDataDescriptor(_currentDesc_) is *true*, then
@@ -6407,15 +6526,15 @@
CreateListFromArrayLike (
_obj_: an ECMAScript language value,
- optional _elementTypes_: a List of names of ECMAScript Language Types,
+ optional _validElementTypes_: ~all~ or ~property-key~,
): either a normal completion containing a List of ECMAScript language values or a throw completion
- description
- - It is used to create a List value whose elements are provided by the indexed properties of _obj_. _elementTypes_ contains the names of ECMAScript Language Types that are allowed for element values of the List that is created.
+ - It is used to create a List value whose elements are provided by the indexed properties of _obj_. _validElementTypes_ indicates the types of values that are allowed as elements.
- 1. If _elementTypes_ is not present, set _elementTypes_ to « Undefined, Null, Boolean, String, Symbol, Number, BigInt, Object ».
+ 1. If _validElementTypes_ is not present, set _validElementTypes_ to ~all~.
1. If _obj_ is not an Object, throw a *TypeError* exception.
1. Let _len_ be ? LengthOfArrayLike(_obj_).
1. Let _list_ be a new empty List.
@@ -6423,7 +6542,7 @@
1. Repeat, while _index_ < _len_,
1. Let _indexName_ be ! ToString(𝔽(_index_)).
1. Let _next_ be ? Get(_obj_, _indexName_).
- 1. If _elementTypes_ does not contain Type(_next_), throw a *TypeError* exception.
+ 1. If _validElementTypes_ is ~property-key~ and _next_ is not a property key, throw a *TypeError* exception.
1. Append _next_ to _list_.
1. Set _index_ to _index_ + 1.
1. Return _list_.
@@ -6470,7 +6589,7 @@
1. Let _P_ be ? Get(_C_, *"prototype"*).
1. If _P_ is not an Object, throw a *TypeError* exception.
1. Repeat,
- 1. Set _O_ to ? _O_.[[GetPrototypeOf]] ().
+ 1. Set _O_ to ? _O_.[[GetPrototypeOf]]() .
1. If _O_ is *null*, return *false*.
1. If SameValue(_P_, _O_) is *true*, return *true*.
@@ -6485,13 +6604,13 @@
- description
- - It is used to retrieve the constructor that should be used to create new objects that are derived from _O_. _defaultConstructor_ is the constructor to use if a constructor @@species property cannot be found starting from _O_.
+ - It is used to retrieve the constructor that should be used to create new objects that are derived from _O_. _defaultConstructor_ is the constructor to use if a constructor %Symbol.species% property cannot be found starting from _O_.
1. Let _C_ be ? Get(_O_, *"constructor"*).
1. If _C_ is *undefined*, return _defaultConstructor_.
1. If _C_ is not an Object, throw a *TypeError* exception.
- 1. Let _S_ be ? Get(_C_, @@species).
+ 1. Let _S_ be ? Get(_C_, %Symbol.species%).
1. If _S_ is either *undefined* or *null*, return _defaultConstructor_.
1. If IsConstructor(_S_) is *true*, return _S_.
1. Throw a *TypeError* exception.
@@ -6508,11 +6627,11 @@
- 1. Let _ownKeys_ be ? _O_.[[OwnPropertyKeys]] ().
+ 1. Let _ownKeys_ be ? _O_.[[OwnPropertyKeys]]() .
1. Let _results_ be a new empty List.
1. For each element _key_ of _ownKeys_, do
1. If _key_ is a String, then
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_key_).
+ 1. Let _desc_ be ? _O_.[[GetOwnProperty]](_key_) .
1. If _desc_ is not *undefined* and _desc_.[[Enumerable]] is *true*, then
1. If _kind_ is ~key~, then
1. Append _key_ to _results_.
@@ -6545,6 +6664,7 @@
1. If _obj_ is a Proxy exotic object, then
1. Perform ? ValidateNonRevokedProxy(_obj_).
1. Let _proxyTarget_ be _obj_.[[ProxyTarget]].
+ 1. Assert: _proxyTarget_ is a function object.
1. Return ? GetFunctionRealm(_proxyTarget_).
1. [id="step-getfunctionrealm-default-return"] Return the current Realm Record.
@@ -6566,14 +6686,14 @@
1. If _source_ is either *undefined* or *null*, return ~unused~.
1. Let _from_ be ! ToObject(_source_).
- 1. Let _keys_ be ? _from_.[[OwnPropertyKeys]] ().
+ 1. Let _keys_ be ? _from_.[[OwnPropertyKeys]]() .
1. For each element _nextKey_ of _keys_, do
1. Let _excluded_ be *false*.
1. For each element _e_ of _excludedItems_, do
1. If SameValue(_e_, _nextKey_) is *true*, then
1. Set _excluded_ to *true*.
1. If _excluded_ is *false*, then
- 1. Let _desc_ be ? _from_.[[GetOwnProperty]] (_nextKey_).
+ 1. Let _desc_ be ? _from_.[[GetOwnProperty]](_nextKey_) .
1. If _desc_ is not *undefined* and _desc_.[[Enumerable]] is *true*, then
1. Let _propValue_ be ? Get(_from_, _nextKey_).
1. Perform ! CreateDataPropertyOrThrow(_target_, _nextKey_, _propValue_).
@@ -6696,10 +6816,9 @@
1. Let _entry_ be PrivateElementFind(_O_, _P_).
1. If _entry_ is ~empty~, throw a *TypeError* exception.
+ 1. If _entry_.[[Kind]] is ~method~, throw a *TypeError* exception.
1. If _entry_.[[Kind]] is ~field~, then
1. Set _entry_.[[Value]] to _value_.
- 1. Else if _entry_.[[Kind]] is ~method~, then
- 1. Throw a *TypeError* exception.
1. Else,
1. Assert: _entry_.[[Kind]] is ~accessor~.
1. If _entry_.[[Set]] is *undefined*, throw a *TypeError* exception.
@@ -6738,16 +6857,16 @@
InitializeInstanceElements (
_O_: an Object,
- _constructor_: an ECMAScript function object,
+ _constructor_: an ECMAScript function object or a built-in function object,
): either a normal completion containing ~unused~ or a throw completion
- 1. Let _methods_ be the value of _constructor_.[[PrivateMethods]].
+ 1. Let _methods_ be _constructor_.[[PrivateMethods]].
1. For each PrivateElement _method_ of _methods_, do
1. Perform ? PrivateMethodOrAccessorAdd(_O_, _method_).
- 1. Let _fields_ be the value of _constructor_.[[Fields]].
+ 1. Let _fields_ be _constructor_.[[Fields]].
1. For each element _fieldRecord_ of _fields_, do
1. Perform ? DefineField(_O_, _fieldRecord_).
1. Return ~unused~.
@@ -6780,15 +6899,15 @@
GroupBy (
_items_: an ECMAScript language value,
- _callbackfn_: an ECMAScript language value,
- _keyCoercion_: ~property~ or ~zero~,
+ _callback_: an ECMAScript language value,
+ _keyCoercion_: ~property~ or ~collection~,
): either a normal completion containing a List of Records with fields [[Key]] (an ECMAScript language value) and [[Elements]] (a List of ECMAScript language values), or a throw completion
1. Perform ? RequireObjectCoercible(_items_).
- 1. If IsCallable(_callbackfn_) is *false*, throw a *TypeError* exception.
+ 1. If IsCallable(_callback_) is *false*, throw a *TypeError* exception.
1. Let _groups_ be a new empty List.
1. Let _iteratorRecord_ be ? GetIterator(_items_, ~sync~).
1. Let _k_ be 0.
@@ -6800,18 +6919,61 @@
1. If _next_ is ~done~, then
1. Return _groups_.
1. Let _value_ be _next_.
- 1. Let _key_ be Completion(Call(_callbackfn_, *undefined*, « _value_, 𝔽(_k_) »)).
+ 1. Let _key_ be Completion(Call(_callback_, *undefined*, « _value_, 𝔽(_k_) »)).
1. IfAbruptCloseIterator(_key_, _iteratorRecord_).
1. If _keyCoercion_ is ~property~, then
1. Set _key_ to Completion(ToPropertyKey(_key_)).
1. IfAbruptCloseIterator(_key_, _iteratorRecord_).
1. Else,
- 1. Assert: _keyCoercion_ is ~zero~.
- 1. If _key_ is *-0*𝔽, set _key_ to *+0*𝔽.
+ 1. Assert: _keyCoercion_ is ~collection~.
+ 1. Set _key_ to CanonicalizeKeyedCollectionKey(_key_).
1. Perform AddValueToKeyedGroup(_groups_, _key_, _value_).
1. Set _k_ to _k_ + 1.
+
+
+
+ GetOptionsObject (
+ _options_: an ECMAScript language value,
+ ): either a normal completion containing an Object or a throw completion
+
+
+
+
+ 1. If _options_ is *undefined*, then
+ 1. Return OrdinaryObjectCreate(*null*).
+ 1. If _options_ is an Object, then
+ 1. Return _options_.
+ 1. Throw a *TypeError* exception.
+
+
+
+
+
+ SetterThatIgnoresPrototypeProperties (
+ _thisValue_: an ECMAScript language value,
+ _home_: an Object,
+ _p_: a property key,
+ _v_: an ECMAScript language value,
+ ): either a normal completion containing ~unused~ or a throw completion
+
+
+
+
+ 1. If _thisValue_ is not an Object, then
+ 1. Throw a *TypeError* exception.
+ 1. If SameValue(_thisValue_, _home_) is *true*, then
+ 1. NOTE: Throwing here emulates assignment to a non-writable data property on the _home_ object in strict mode code.
+ 1. Throw a *TypeError* exception.
+ 1. Let _desc_ be ? _thisValue_.[[GetOwnProperty]](_p_).
+ 1. If _desc_ is *undefined*, then
+ 1. Perform ? CreateDataPropertyOrThrow(_thisValue_, _p_, _v_).
+ 1. Else,
+ 1. Perform ? Set(_thisValue_, _p_, _v_, *true*).
+ 1. Return ~unused~.
+
+
@@ -6820,21 +6982,23 @@ Operations on Iterator Objects
Iterator Records
- An Iterator Record is a Record value used to encapsulate an Iterator or AsyncIterator along with the `next` method.
+ An Iterator Record is a Record value used to encapsulate an iterator or async iterator along with the `next` method.
Iterator Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Iterator]]
@@ -6843,7 +7007,7 @@ Iterator Records
an Object
- An object that conforms to the Iterator or AsyncIterator interface.
+ An object that conforms to the iterator interface or the async iterator interface.
@@ -6872,6 +7036,21 @@ Iterator Records
+
+
+ GetIteratorDirect (
+ _obj_: an Object,
+ ): either a normal completion containing an Iterator Record or a throw completion
+
+
+
+
+ 1. Let _nextMethod_ be ? Get(_obj_, *"next"*).
+ 1. Let _iteratorRecord_ be the Iterator Record { [[Iterator]]: _obj_, [[NextMethod]]: _nextMethod_, [[Done]]: *false* }.
+ 1. Return _iteratorRecord_.
+
+
+
GetIteratorFromMethod (
@@ -6884,9 +7063,7 @@
1. Let _iterator_ be ? Call(_method_, _obj_).
1. If _iterator_ is not an Object, throw a *TypeError* exception.
- 1. Let _nextMethod_ be ? Get(_iterator_, *"next"*).
- 1. Let _iteratorRecord_ be the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: _nextMethod_, [[Done]]: *false* }.
- 1. Return _iteratorRecord_.
+ 1. Return ? GetIteratorDirect(_iterator_).
@@ -6901,19 +7078,43 @@
1. If _kind_ is ~async~, then
- 1. Let _method_ be ? GetMethod(_obj_, @@asyncIterator).
+ 1. Let _method_ be ? GetMethod(_obj_, %Symbol.asyncIterator%).
1. If _method_ is *undefined*, then
- 1. Let _syncMethod_ be ? GetMethod(_obj_, @@iterator).
+ 1. Let _syncMethod_ be ? GetMethod(_obj_, %Symbol.iterator%).
1. If _syncMethod_ is *undefined*, throw a *TypeError* exception.
1. Let _syncIteratorRecord_ be ? GetIteratorFromMethod(_obj_, _syncMethod_).
1. Return CreateAsyncFromSyncIterator(_syncIteratorRecord_).
1. Else,
- 1. Let _method_ be ? GetMethod(_obj_, @@iterator).
+ 1. Let _method_ be ? GetMethod(_obj_, %Symbol.iterator%).
1. If _method_ is *undefined*, throw a *TypeError* exception.
1. Return ? GetIteratorFromMethod(_obj_, _method_).
+
+
+ GetIteratorFlattenable (
+ _obj_: an ECMAScript language value,
+ _primitiveHandling_: ~iterate-string-primitives~ or ~reject-primitives~,
+ ): either a normal completion containing an Iterator Record or a throw completion
+
+
+
+
+ 1. If _obj_ is not an Object, then
+ 1. If _primitiveHandling_ is ~reject-primitives~, throw a *TypeError* exception.
+ 1. Assert: _primitiveHandling_ is ~iterate-string-primitives~.
+ 1. If _obj_ is not a String, throw a *TypeError* exception.
+ 1. Let _method_ be ? GetMethod(_obj_, %Symbol.iterator%).
+ 1. If _method_ is *undefined*, then
+ 1. Let _iterator_ be _obj_.
+ 1. Else,
+ 1. Let _iterator_ be ? Call(_method_, _obj_).
+ 1. If _iterator_ is not an Object, throw a *TypeError* exception.
+ 1. Return ? GetIteratorDirect(_iterator_).
+
+
+
IteratorNext (
@@ -6942,26 +7143,26 @@
IteratorComplete (
- _iterResult_: an Object,
+ _iteratorResult_: an Object,
): either a normal completion containing a Boolean or a throw completion
- 1. Return ToBoolean(? Get(_iterResult_, *"done"*)).
+ 1. Return ToBoolean(? Get(_iteratorResult_, *"done"*)).
IteratorValue (
- _iterResult_: an Object,
+ _iteratorResult_: an Object,
): either a normal completion containing an ECMAScript language value or a throw completion
- 1. Return ? Get(_iterResult_, *"value"*).
+ 1. Return ? Get(_iteratorResult_, *"value"*).
@@ -7036,6 +7237,24 @@
+
+
+ IteratorCloseAll (
+ _iters_: a List of Iterator Records,
+ _completion_: a Completion Record,
+ ): a Completion Record
+
+
+ - skip global checks
+ - true
+
+
+ 1. For each element _iter_ of _iters_, in reverse List order, do
+ 1. Set _completion_ to Completion(IteratorClose(_iter_, _completion_)).
+ 1. Return ? _completion_.
+
+
+
IfAbruptCloseIterator ( _value_, _iteratorRecord_ )
IfAbruptCloseIterator is a shorthand for a sequence of algorithm steps that use an Iterator Record. An algorithm step of the form:
@@ -7046,7 +7265,7 @@ IfAbruptCloseIterator ( _value_, _iteratorRecord_ )
1. Assert: _value_ is a Completion Record.
1. If _value_ is an abrupt completion, return ? IteratorClose(_iteratorRecord_, _value_).
- 1. Else, set _value_ to ! _value_.
+ 1. Set _value_ to ! _value_.
@@ -7077,16 +7296,30 @@
+
+ IfAbruptCloseAsyncIterator ( _value_, _iteratorRecord_ )
+ IfAbruptCloseAsyncIterator is a shorthand for a sequence of algorithm steps that use an Iterator Record. An algorithm step of the form:
+
+ 1. IfAbruptCloseAsyncIterator(_value_, _iteratorRecord_).
+
+ means the same thing as:
+
+ 1. Assert: _value_ is a Completion Record.
+ 1. If _value_ is an abrupt completion, return ? AsyncIteratorClose(_iteratorRecord_, _value_).
+ 1. Set _value_ to ! _value_.
+
+
+
- CreateIterResultObject (
+ CreateIteratorResultObject (
_value_: an ECMAScript language value,
_done_: a Boolean,
- ): an Object that conforms to the IteratorResult interface
+ ): an Object that conforms to the IteratorResult interface
- description
- - It creates an object that conforms to the IteratorResult interface.
+ - It creates an object that conforms to the IteratorResult interface.
1. Let _obj_ be OrdinaryObjectCreate(%Object.prototype%).
@@ -7104,15 +7337,15 @@
- description
- - It creates an Iterator (
+ - It creates an Iterator Record whose [[NextMethod]] returns the successive elements of _list_.
1. Let _closure_ be a new Abstract Closure with no parameters that captures _list_ and performs the following steps when called:
1. For each element _E_ of _list_, do
- 1. Perform ? GeneratorYield(CreateIterResultObject(_E_, *false*)).
+ 1. Perform ? GeneratorYield(CreateIteratorResultObject(_E_, *false*)).
1. Return NormalCompletion(*undefined*).
- 1. Let _iterator_ be CreateIteratorFromClosure(_closure_, ~empty~, %IteratorPrototype%).
- 1. Return the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: %GeneratorFunction.prototype.prototype.next%, [[Done]]: *false* }.
+ 1. Let _iterator_ be CreateIteratorFromClosure(_closure_, ~empty~, %Iterator.prototype%).
+ 1. Return the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: %GeneratorPrototype.next%, [[Done]]: *false* }.
The list iterator object is never directly accessible to ECMAScript code.
@@ -7340,11 +7573,11 @@ Static Semantics: BoundNames ( ): a List of Strings
1. Let _head_ be the |AsyncArrowHead| that is covered by |CoverCallExpressionAndAsyncArrowHead|.
1. Return the BoundNames of _head_.
- ImportDeclaration : `import` ImportClause FromClause `;`
+ ImportDeclaration : `import` ImportClause FromClause WithClause? `;`
1. Return the BoundNames of |ImportClause|.
- ImportDeclaration : `import` ModuleSpecifier `;`
+ ImportDeclaration : `import` ModuleSpecifier WithClause? `;`
1. Return a new empty List.
@@ -7376,7 +7609,7 @@ Static Semantics: BoundNames ( ): a List of Strings
ExportDeclaration :
- `export` ExportFromClause FromClause `;`
+ `export` ExportFromClause FromClause WithClause? `;`
`export` NamedExports `;`
@@ -7734,7 +7967,7 @@ Static Semantics: LexicallyScopedDeclarations ( ): a List of Parse Nodes
ExportDeclaration :
- `export` ExportFromClause FromClause `;`
+ `export` ExportFromClause FromClause WithClause? `;`
`export` NamedExports `;`
`export` VariableStatement
@@ -8575,8 +8808,8 @@
BreakStatement : `break` LabelIdentifier `;`
- 1. If _labelSet_ does not contain the StringValue of |LabelIdentifier|, return *true*.
- 1. Return *false*.
+ 1. If _labelSet_ contains the StringValue of |LabelIdentifier|, return *false*.
+ 1. Return *true*.
WithStatement : `with` `(` Expression `)` Statement
@@ -8764,8 +8997,8 @@
ContinueStatement : `continue` LabelIdentifier `;`
- 1. If _iterationSet_ does not contain the StringValue of |LabelIdentifier|, return *true*.
- 1. Return *false*.
+ 1. If _iterationSet_ contains the StringValue of |LabelIdentifier|, return *false*.
+ 1. Return *true*.
WithStatement : `with` `(` Expression `)` Statement
@@ -9175,9 +9408,8 @@
ClassExpression : `class` ClassTail
- 1. Let _value_ be ? ClassDefinitionEvaluation of |ClassTail| with arguments *undefined* and _name_.
- 1. Set _value_.[[SourceText]] to the source text matched by |ClassExpression|.
- 1. Return _value_.
+ 1. Let _sourceText_ be the source text matched by |ClassExpression|.
+ 1. Return ? ClassDefinitionEvaluation of |ClassTail| with arguments *undefined*, _name_, and _sourceText_.
@@ -9241,7 +9473,8 @@
1. If _symbol_ is |ClassBody|, return *true*.
1. If _symbol_ is |ClassHeritage|, then
- 1. If |ClassHeritage| is present, return *true*; otherwise return *false*.
+ 1. If |ClassHeritage| is present, return *true*.
+ 1. Return *false*.
1. If |ClassHeritage| is present, then
1. If |ClassHeritage| Contains _symbol_ is *true*, return *true*.
1. Return the result of ComputedPropertyContains of |ClassBody| with argument _symbol_.
@@ -9509,9 +9742,8 @@
1. If _environment_ is not *undefined*, then
1. Perform ! _environment_.InitializeBinding(_name_, _value_).
1. Return ~unused~.
- 1. Else,
- 1. Let _lhs_ be ? ResolveBinding(_name_).
- 1. Return ? PutValue(_lhs_, _value_).
+ 1. Let _lhs_ be ? ResolveBinding(_name_).
+ 1. Return ? PutValue(_lhs_, _value_).
@@ -9664,7 +9896,7 @@
- Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
+ Static Semantics: AssignmentTargetType ( ): ~simple~, ~web-compat~, or ~invalid~
IdentifierReference : Identifier
@@ -9699,6 +9931,16 @@ Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
1. Let _expr_ be the |ParenthesizedExpression| that is covered by |CoverParenthesizedExpressionAndArrowParameterList|.
1. Return the AssignmentTargetType of _expr_.
+
+ CallExpression :
+ CoverCallExpressionAndAsyncArrowHead
+ CallExpression Arguments
+
+
+ 1. [id="step-assignmenttargettype-web-compat", normative-optional] If the host is a web browser or otherwise supports
PrimaryExpression :
`this`
@@ -9714,10 +9956,8 @@ Static Semantics: AssignmentTargetType ( ): ~simple~ or ~invalid~
TemplateLiteral
CallExpression :
- CoverCallExpressionAndAsyncArrowHead
SuperCall
ImportCall
- CallExpression Arguments
CallExpression TemplateLiteral
NewExpression :
@@ -9837,11 +10077,19 @@ Static Semantics: PropName ( ): a String or ~empty~
1. Return the PropName of |PropertyName|.
- LiteralPropertyName : IdentifierName
+
+ LiteralPropertyName : IdentifierName
+
+ AttributeKey : IdentifierName
+
1. Return the StringValue of |IdentifierName|.
- LiteralPropertyName : StringLiteral
+
+ LiteralPropertyName : StringLiteral
+
+ AttributeKey : StringLiteral
+
1. Return the SV of |StringLiteral|.
@@ -9939,94 +10187,163 @@ The Environment Record Type Hierarchy
The Environment Record abstract class includes the abstract specification methods defined in
-
+
-
-
- Method
-
-
- Purpose
-
+
+
+
+ Method
+
+
+ Purpose
+
+
+ Definitions
+
+
+
+
+
+ HasBinding (
+ _N_: a String,
+ ): either a normal completion containing a Boolean or a throw completion
+
+
+ It determines if an Environment Record has a binding for _N_.
+
+
+ It has concrete definitions in the following types:
+
-
+
+
+ CreateMutableBinding (
+ _N_: a String,
+ _D_: a Boolean,
+ ): either a normal completion containing ~unused~ or a throw completion
+
- HasBinding(N)
+ It creates a new but uninitialized mutable binding in an Environment Record. _N_ is the text of the bound name. If _D_ is *true* the binding may be subsequently deleted.
- Determine if an Environment Record has a binding for the String value _N_. Return *true* if it does and *false* if it does not.
+ It has concrete definitions in the following types:
+
-
+
+
+ CreateImmutableBinding (
+ _N_: a String,
+ _S_: a Boolean,
+ ): either a normal completion containing ~unused~ or a throw completion
+
- CreateMutableBinding(N, D)
+ It creates a new but uninitialized immutable binding in an Environment Record. _N_ is the text of the bound name. If _S_ is *true* then attempts to set it after it has been initialized will always throw an exception, regardless of the strict mode setting of operations that reference that binding.
- Create a new but uninitialized mutable binding in an Environment Record. The String value _N_ is the text of the bound name. If the Boolean argument _D_ is *true* the binding may be subsequently deleted.
+ It has concrete definitions in the following types:
+
-
+
+
+ InitializeBinding (
+ _N_: a String,
+ _V_: an ECMAScript language value,
+ ): either a normal completion containing ~unused~ or a throw completion
+
- CreateImmutableBinding(N, S)
+ It sets the value of an already existing but uninitialized binding in an Environment Record. _N_ is the text of the bound name. _V_ is the value for the binding.
- Create a new but uninitialized immutable binding in an Environment Record. The String value _N_ is the text of the bound name. If _S_ is *true* then attempts to set it after it has been initialized will always throw an exception, regardless of the strict mode setting of operations that reference that binding.
+ It has concrete definitions in the following types:
+
-
+
- InitializeBinding(N, V)
+ SetMutableBinding (
+ _N_: a String,
+ _V_: an ECMAScript language value,
+ _S_: a Boolean,
+ ): either a normal completion containing ~unused~ or a throw completion
- Set the value of an already existing but uninitialized binding in an Environment Record. The String value _N_ is the text of the bound name. _V_ is the value for the binding and is a value of any ECMAScript language type.
+ It sets the value of an already existing mutable binding in an Environment Record. _N_ is the text of the bound name. _V_ is the value for the binding. If _S_ is *true* and the binding cannot be set, this will throw a *TypeError* exception.
+
+
+ It has concrete definitions in the following types:
+
-
+
- SetMutableBinding(N, V, S)
+ GetBindingValue (
+ _N_: a String,
+ _S_: a Boolean,
+ ): either a normal completion containing an ECMAScript language value or a throw completion
- Set the value of an already existing mutable binding in an Environment Record. The String value _N_ is the text of the bound name. _V_ is the value for the binding and may be a value of any ECMAScript language type. _S_ is a Boolean flag. If _S_ is *true* and the binding cannot be set throw a *TypeError* exception.
+ It returns the value of an already existing binding from an Environment Record. _N_ is the text of the bound name. _S_ is used to identify references originating in strict mode code or that otherwise require strict mode reference semantics. If _S_ is *true* and the binding does not exist, this will throw a *ReferenceError* exception. If the binding exists but is uninitialized a *ReferenceError* is thrown, regardless of the value of _S_.
+
+
+ It has concrete definitions in the following types:
+
-
+
+
+ DeleteBinding (
+ _N_: a String,
+ ): either a normal completion containing a Boolean or a throw completion
+
- GetBindingValue(N, S)
+ It deletes a binding from an Environment Record. _N_ is the text of the bound name. If a binding for _N_ exists, this removes the binding and returns *true*. If the binding exists but cannot be removed, this returns *false*. If the binding does not exist, this returns *true*.
- Returns the value of an already existing binding from an Environment Record. The String value _N_ is the text of the bound name. _S_ is used to identify references originating in strict mode code or that otherwise require strict mode reference semantics. If _S_ is *true* and the binding does not exist throw a *ReferenceError* exception. If the binding exists but is uninitialized a *ReferenceError* is thrown, regardless of the value of _S_.
+ It has concrete definitions in the following types:
+
-
+
+ HasThisBinding ( ): a Boolean
- DeleteBinding(N)
+ It determines if an Environment Record establishes a `this` binding. This returns *true* if it does and *false* if it does not.
- Delete a binding from an Environment Record. The String value _N_ is the text of the bound name. If a binding for _N_ exists, remove the binding and return *true*. If the binding exists but cannot be removed return *false*. If the binding does not exist return *true*.
+ It has concrete definitions in the following types:
+
-
+
+ GetThisBinding ( ): either a normal completion containing an ECMAScript language value or a throw completion
- HasThisBinding()
+ It returns the value of this Environment Record's `this` binding. It throws a *ReferenceError* if the `this` binding has not been initialized.
- Determine if an Environment Record establishes a `this` binding. Return *true* if it does and *false* if it does not.
+ It has concrete definitions in the following types:
+
-
+
+ HasSuperBinding ( ): a Boolean
- HasSuperBinding()
+ It determines if an Environment Record establishes a `super` method binding. This returns *true* if it does and *false* if it does not. If it returns *true* it implies that the Environment Record is a Function Environment Record, although the reverse implication does not hold.
- Determine if an Environment Record establishes a `super` method binding. Return *true* if it does and *false* if it does not.
+ It has concrete definitions in the following types:
+
-
+
+ WithBaseObject ( ): an Object or *undefined*
- WithBaseObject()
+ If this Environment Record is associated with a `with` statement, it returns the with object. Otherwise, it returns *undefined*.
- If this Environment Record is associated with a `with` statement, return the with object. Otherwise, return *undefined*.
+ It has concrete definitions in the following types:
+
@@ -10035,7 +10352,6 @@ The Environment Record Type Hierarchy
Declarative Environment Records
Each Declarative Environment Record is associated with an ECMAScript program scope containing variable, constant, let, class, module, import, and/or function declarations. A Declarative Environment Record binds the set of identifiers defined by the declarations contained within its scope.
- The behaviour of the concrete specification methods for Declarative Environment Records is defined by the following algorithms.
@@ -10213,6 +10529,11 @@ HasThisBinding ( ): *false*
+
+ GetThisBinding ( )
+ The GetThisBinding concrete method of a Declarative Environment Record is never used within this specification.
+
+
HasSuperBinding ( ): *false*
@@ -10246,17 +10567,19 @@ Object Environment Records
Object Environment Records have the additional state fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[BindingObject]]
@@ -10281,7 +10604,6 @@ Object Environment Records
- The behaviour of the concrete specification methods for Object Environment Records is defined by the following algorithms.
@@ -10301,7 +10623,7 @@
1. Let _foundBinding_ be ? HasProperty(_bindingObject_, _N_).
1. If _foundBinding_ is *false*, return *false*.
1. If _envRec_.[[IsWithEnvironment]] is *false*, return *true*.
- 1. Let _unscopables_ be ? Get(_bindingObject_, @@unscopables).
+ 1. Let _unscopables_ be ? Get(_bindingObject_, %Symbol.unscopables%).
1. If _unscopables_ is an Object, then
1. Let _blocked_ be ToBoolean(? Get(_unscopables_, _N_)).
1. If _blocked_ is *true*, return *false*.
@@ -10353,7 +10675,7 @@
- It is used to set the bound value of the current binding of the identifier whose name is _N_ to the value _V_.
- 1. Perform ? _envRec_.SetMutableBinding (_N_, _V_, *false*).
+ 1. Perform ? _envRec_.SetMutableBinding(_N_, _V_, *false*) .
1. Return ~unused~.
@@ -10403,7 +10725,8 @@
1. Let _bindingObject_ be _envRec_.[[BindingObject]].
1. Let _value_ be ? HasProperty(_bindingObject_, _N_).
1. If _value_ is *false*, then
- 1. If _S_ is *false*, return *undefined*; otherwise throw a *ReferenceError* exception.
+ 1. If _S_ is *false*, return *undefined*.
+ 1. Throw a *ReferenceError* exception.
1. Return ? Get(_bindingObject_, _N_).
@@ -10423,7 +10746,7 @@
1. Let _bindingObject_ be _envRec_.[[BindingObject]].
- 1. Return ? _bindingObject_.[[Delete]] (_N_).
+ 1. Return ? _bindingObject_.[[Delete]](_N_) .
@@ -10441,6 +10764,11 @@ HasThisBinding ( ): *false*
+
+ GetThisBinding ( )
+ The GetThisBinding concrete method of an Object Environment Record is never used within this specification.
+
+
HasSuperBinding ( ): *false*
@@ -10463,7 +10791,7 @@ WithBaseObject ( ): an Object or *undefined*
1. If _envRec_.[[IsWithEnvironment]] is *true*, return _envRec_.[[BindingObject]].
- 1. Otherwise, return *undefined*.
+ 1. Return *undefined*.
@@ -10474,17 +10802,19 @@ Function Environment Records
Function Environment Records have the additional state fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[ThisValue]]
@@ -10523,7 +10853,7 @@ Function Environment Records
[[NewTarget]]
- an Object or *undefined*
+ a constructor or *undefined*
If this Environment Record was created by the [[Construct]] internal method, [[NewTarget]] is the value of the [[Construct]] _newTarget_ parameter. Otherwise, its value is *undefined*.
@@ -10531,61 +10861,25 @@ Function Environment Records
- Function Environment Records support all of the Declarative Environment Record methods listed in
-
-
-
-
- Method
-
-
- Purpose
-
-
-
-
- BindThisValue(V)
-
-
- Set the [[ThisValue]] and record that it has been initialized.
-
-
-
-
- GetThisBinding()
-
-
- Return the value of this Environment Record's `this` binding. Throws a *ReferenceError* if the `this` binding has not been initialized.
-
-
-
-
- GetSuperBase()
-
-
- Return the object that is the base for `super` property accesses bound in this Environment Record. The value *undefined* indicates that such accesses will produce runtime errors.
-
-
-
-
- The behaviour of the additional concrete specification methods for Function Environment Records is defined by the following algorithms:
+ Function Environment Records support all of the Declarative Environment Record methods listed in
-
+
BindThisValue (
+ _envRec_: a Function Environment Record,
_V_: an ECMAScript language value,
- ): either a normal completion containing an ECMAScript language value or a throw completion
+ ): either a normal completion containing ~unused~ or a throw completion
- - for
- - a Function Environment Record _envRec_
+ - description
+ - It sets the _envRec_.[[ThisValue]] and records that it has been initialized.
1. Assert: _envRec_.[[ThisBindingStatus]] is not ~lexical~.
1. If _envRec_.[[ThisBindingStatus]] is ~initialized~, throw a *ReferenceError* exception.
1. Set _envRec_.[[ThisValue]] to _V_.
1. Set _envRec_.[[ThisBindingStatus]] to ~initialized~.
- 1. Return _V_.
+ 1. Return ~unused~.
@@ -10595,20 +10889,9 @@ HasThisBinding ( ): a Boolean
- for
- a Function Environment Record _envRec_
-
- 1. If _envRec_.[[ThisBindingStatus]] is ~lexical~, return *false*; otherwise, return *true*.
-
-
-
-
- HasSuperBinding ( ): a Boolean
-
- - for
- - a Function Environment Record _envRec_
-
1. If _envRec_.[[ThisBindingStatus]] is ~lexical~, return *false*.
- 1. If _envRec_.[[FunctionObject]].[[HomeObject]] is *undefined*, return *false*; otherwise, return *true*.
+ 1. Return *true*.
@@ -10625,17 +10908,34 @@ GetThisBinding ( ): either a normal completion containing an ECMAScript lang
-
- GetSuperBase ( ): either a normal completion containing either an Object, *null*, or *undefined*, or a throw completion
+
+ HasSuperBinding ( ): a Boolean
- for
- a Function Environment Record _envRec_
+
+ 1. If _envRec_.[[ThisBindingStatus]] is ~lexical~, return *false*.
+ 1. If _envRec_.[[FunctionObject]].[[HomeObject]] is *undefined*, return *false*.
+ 1. Return *true*.
+
+
+
+
+
+ GetSuperBase (
+ _envRec_: a Function Environment Record,
+ ): an Object, *null*, or *undefined*
+
+
+ - description
+ - It returns the object that is the base for `super` property accesses bound in _envRec_. The value *undefined* indicates that such accesses will produce runtime errors.
+
1. Let _home_ be _envRec_.[[FunctionObject]].[[HomeObject]].
1. If _home_ is *undefined*, return *undefined*.
- 1. Assert: _home_ is an Object.
- 1. Return ? _home_.[[GetPrototypeOf]] ().
+ 1. Assert: _home_ is an ordinary object.
+ 1. Return ! _home_.[[GetPrototypeOf]]().
@@ -10644,21 +10944,23 @@ GetSuperBase ( ): either a normal completion containing either an Object, *n
Global Environment Records
A Global Environment Record is used to represent the outer most scope that is shared by all of the ECMAScript |Script| elements that are processed in a common realm. A Global Environment Record provides the bindings for built-in globals (clause
A Global Environment Record is logically a single record but it is specified as a composite encapsulating an Object Environment Record and a Declarative Environment Record. The Object Environment Record has as its base object the global object of the associated Realm Record. This global object is the value returned by the Global Environment Record's GetThisBinding concrete method. The Object Environment Record component of a Global Environment Record contains the bindings for all built-in globals (clause
- Properties may be created directly on a global object. Hence, the Object Environment Record component of a Global Environment Record may contain both bindings created explicitly by |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, or |VariableDeclaration| declarations and bindings created implicitly as properties of the global object. In order to identify which bindings were explicitly created using declarations, a Global Environment Record maintains a list of the names bound using its CreateGlobalVarBinding and CreateGlobalFunctionBinding concrete methods.
- Global Environment Records have the additional fields listed in
+ Properties may be created directly on a global object. Hence, the Object Environment Record component of a Global Environment Record may contain both bindings created explicitly by |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, or |VariableDeclaration| declarations and bindings created implicitly as properties of the global object. In order to identify which bindings were explicitly created using declarations, a Global Environment Record maintains a list of the names bound using the CreateGlobalVarBinding and CreateGlobalFunctionBinding abstract operations.
+ Global Environment Records have the additional fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[ObjectRecord]]
@@ -10692,96 +10994,8 @@ Global Environment Records
Contains bindings for all declarations in global code for the associated realm code except for |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, and |VariableDeclaration| bindings.
-
-
- [[VarNames]]
-
-
- a List of Strings
-
-
- The string names bound by |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, |AsyncGeneratorDeclaration|, and |VariableDeclaration| declarations in global code for the associated realm.
-
-
-
-
-
-
- Method
-
-
- Purpose
-
-
-
-
- GetThisBinding()
-
-
- Return the value of this Environment Record's `this` binding.
-
-
-
-
- HasVarDeclaration (N)
-
-
- Determines if the argument identifier has a binding in this Environment Record that was created using a |VariableDeclaration|, |FunctionDeclaration|, |GeneratorDeclaration|, |AsyncFunctionDeclaration|, or |AsyncGeneratorDeclaration|.
-
-
-
-
- HasLexicalDeclaration (N)
-
-
- Determines if the argument identifier has a binding in this Environment Record that was created using a lexical declaration such as a |LexicalDeclaration| or a |ClassDeclaration|.
-
-
-
-
- HasRestrictedGlobalProperty (N)
-
-
- Determines if the argument is the name of a global object property that may not be shadowed by a global lexical binding.
-
-
-
-
- CanDeclareGlobalVar (N)
-
-
- Determines if a corresponding CreateGlobalVarBinding call would succeed if called for the same argument _N_.
-
-
-
-
- CanDeclareGlobalFunction (N)
-
-
- Determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same argument _N_.
-
-
-
-
- CreateGlobalVarBinding(N, D)
-
-
- Used to create and initialize to *undefined* a global `var` binding in the [[ObjectRecord]] component of a Global Environment Record. The binding will be a mutable binding. The corresponding global object property will have attribute values appropriate for a `var`. The String value _N_ is the bound name. If _D_ is *true*, the binding may be deleted. Logically equivalent to CreateMutableBinding followed by a SetMutableBinding but it allows var declarations to receive special treatment.
-
-
-
-
- CreateGlobalFunctionBinding(N, V, D)
-
-
- Create and initialize a global `function` binding in the [[ObjectRecord]] component of a Global Environment Record. The binding will be a mutable binding. The corresponding global object property will have attribute values appropriate for a `function`. The String value _N_ is the bound name. _V_ is the initialization value. If the Boolean argument _D_ is *true*, the binding may be deleted. Logically equivalent to CreateMutableBinding followed by a SetMutableBinding but it allows function declarations to receive special treatment.
-
-
-
-
- The behaviour of the concrete specification methods for Global Environment Records is defined by the following algorithms.
@@ -10800,7 +11014,7 @@
1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
1. If ! _DclRec_.HasBinding(_N_) is *true*, return *true*.
1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.HasBinding (_N_).
+ 1. Return ? _ObjRec_.HasBinding(_N_) .
@@ -10866,7 +11080,7 @@
1. Return ! _DclRec_.InitializeBinding(_N_, _V_).
1. Assert: If the binding exists, it must be in the Object Environment Record.
1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.InitializeBinding (_N_, _V_).
+ 1. Return ? _ObjRec_.InitializeBinding(_N_, _V_) .
@@ -10890,7 +11104,7 @@
1. If ! _DclRec_.HasBinding(_N_) is *true*, then
1. Return ? _DclRec_.SetMutableBinding(_N_, _V_, _S_).
1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.SetMutableBinding (_N_, _V_, _S_).
+ 1. Return ? _ObjRec_.SetMutableBinding(_N_, _V_, _S_) .
@@ -10913,7 +11127,7 @@
1. If ! _DclRec_.HasBinding(_N_) is *true*, then
1. Return ? _DclRec_.GetBindingValue(_N_, _S_).
1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
- 1. Return ? _ObjRec_.GetBindingValue (_N_, _S_).
+ 1. Return ? _ObjRec_.GetBindingValue(_N_, _S_) .
@@ -10938,10 +11152,7 @@
1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
1. Let _existingProp_ be ? HasOwnProperty(_globalObject_, _N_).
1. If _existingProp_ is *true*, then
- 1. Let _status_ be ? _ObjRec_.DeleteBinding (_N_).
- 1. If _status_ is *true* and _envRec_.[[VarNames]] contains _N_, then
- 1. Remove _N_ from _envRec_.[[VarNames]].
- 1. Return _status_.
+ 1. Return ? _ObjRec_.DeleteBinding(_N_) .
1. Return *true*.
@@ -10960,6 +11171,17 @@ HasThisBinding ( ): *true*
+
+ GetThisBinding ( ): a normal completion containing an Object
+
+ - for
+ - a Global Environment Record _envRec_
+
+
+ 1. Return _envRec_.[[GlobalThisValue]].
+
+
+
HasSuperBinding ( ): *false*
@@ -10985,49 +11207,16 @@ WithBaseObject ( ): *undefined*
-
- GetThisBinding ( ): a normal completion containing an Object
-
- - for
- - a Global Environment Record _envRec_
-
-
- 1. Return _envRec_.[[GlobalThisValue]].
-
-
-
-
-
- HasVarDeclaration (
- _N_: a String,
- ): a Boolean
-
-
- - for
- - a Global Environment Record _envRec_
-
- - description
- - It determines if the argument identifier has a binding in this record that was created using a |VariableStatement| or a |FunctionDeclaration|.
-
-
- 1. Let _varDeclaredNames_ be _envRec_.[[VarNames]].
- 1. If _varDeclaredNames_ contains _N_, return *true*.
- 1. Return *false*.
-
-
-
-
+
HasLexicalDeclaration (
+ _envRec_: a Global Environment Record,
_N_: a String,
): a Boolean
- - for
- - a Global Environment Record _envRec_
-
- description
- - It determines if the argument identifier has a binding in this record that was created using a lexical declaration such as a |LexicalDeclaration| or a |ClassDeclaration|.
+ - It determines if the argument identifier has a binding in _envRec_ that was created using a lexical declaration such as a |LexicalDeclaration| or a |ClassDeclaration|.
1. Let _DclRec_ be _envRec_.[[DeclarativeRecord]].
@@ -11035,23 +11224,21 @@
-
+
HasRestrictedGlobalProperty (
+ _envRec_: a Global Environment Record,
_N_: a String,
): either a normal completion containing a Boolean or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- It determines if the argument identifier is the name of a property of the global object that must not be shadowed by a global lexical binding.
1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]] (_N_).
+ 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]](_N_) .
1. If _existingProp_ is *undefined*, return *false*.
1. If _existingProp_.[[Configurable]] is *true*, return *false*.
1. Return *true*.
@@ -11061,16 +11248,14 @@
-
+
CanDeclareGlobalVar (
+ _envRec_: a Global Environment Record,
_N_: a String,
): either a normal completion containing a Boolean or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- It determines if a corresponding CreateGlobalVarBinding call would succeed if called for the same argument _N_. Redundant var declarations and var declarations for pre-existing global object properties are allowed.
@@ -11083,23 +11268,21 @@
-
+
CanDeclareGlobalFunction (
+ _envRec_: a Global Environment Record,
_N_: a String,
): either a normal completion containing a Boolean or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- It determines if a corresponding CreateGlobalFunctionBinding call would succeed if called for the same argument _N_.
1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]] (_N_).
+ 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]](_N_) .
1. If _existingProp_ is *undefined*, return ? IsExtensible(_globalObject_).
1. If _existingProp_.[[Configurable]] is *true*, return *true*.
1. If IsDataDescriptor(_existingProp_) is *true* and _existingProp_ has attribute values { [[Writable]]: *true*, [[Enumerable]]: *true* }, return *true*.
@@ -11107,19 +11290,17 @@
-
+
CreateGlobalVarBinding (
+ _envRec_: a Global Environment Record,
_N_: a String,
_D_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- - It creates and initializes a mutable binding in the associated Object Environment Record and records the bound name in the associated [[VarNames]] List. If a binding already exists, it is reused and assumed to be initialized.
+ - It creates and initializes a mutable binding in the associated Object Environment Record. If a binding already exists, it is reused and assumed to be initialized.
1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
@@ -11127,41 +11308,35 @@
1. Let _hasProperty_ be ? HasOwnProperty(_globalObject_, _N_).
1. Let _extensible_ be ? IsExtensible(_globalObject_).
1. If _hasProperty_ is *false* and _extensible_ is *true*, then
- 1. Perform ? _ObjRec_.CreateMutableBinding (_N_, _D_).
- 1. Perform ? _ObjRec_.InitializeBinding (_N_, *undefined*).
- 1. If _envRec_.[[VarNames]] does not contain _N_, then
- 1. Append _N_ to _envRec_.[[VarNames]].
+ 1. Perform ? _ObjRec_.CreateMutableBinding(_N_, _D_) .
+ 1. Perform ? _ObjRec_.InitializeBinding(_N_, *undefined*) .
1. Return ~unused~.
-
+
CreateGlobalFunctionBinding (
+ _envRec_: a Global Environment Record,
_N_: a String,
_V_: an ECMAScript language value,
_D_: a Boolean,
): either a normal completion containing ~unused~ or a throw completion
- - for
- - a Global Environment Record _envRec_
-
- description
- - It creates and initializes a mutable binding in the associated Object Environment Record and records the bound name in the associated [[VarNames]] List. If a binding already exists, it is replaced.
+ - It creates and initializes a mutable binding in the associated Object Environment Record. If a binding already exists, it is replaced.
1. Let _ObjRec_ be _envRec_.[[ObjectRecord]].
1. Let _globalObject_ be _ObjRec_.[[BindingObject]].
- 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]] (_N_).
+ 1. Let _existingProp_ be ? _globalObject_.[[GetOwnProperty]](_N_) .
1. If _existingProp_ is *undefined* or _existingProp_.[[Configurable]] is *true*, then
1. Let _desc_ be the PropertyDescriptor { [[Value]]: _V_, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: _D_ }.
1. Else,
1. Let _desc_ be the PropertyDescriptor { [[Value]]: _V_ }.
1. Perform ? DefinePropertyOrThrow(_globalObject_, _N_, _desc_).
1. [id="step-createglobalfunctionbinding-set"] Perform ? Set(_globalObject_, _N_, _V_, *false*).
- 1. If _envRec_.[[VarNames]] does not contain _N_, then
- 1. Append _N_ to _envRec_.[[VarNames]].
1. Return ~unused~.
@@ -11173,36 +11348,7 @@
Module Environment Records
A Module Environment Record is a Declarative Environment Record that is used to represent the outer scope of an ECMAScript |Module|. In additional to normal mutable and immutable bindings, Module Environment Records also provide immutable import bindings which are bindings that provide indirect access to a target binding that exists in another Environment Record.
- Module Environment Records support all of the Declarative Environment Record methods listed in
-
-
-
-
- Method
-
-
- Purpose
-
-
-
-
- CreateImportBinding(N, M, N2)
-
-
- Create an immutable indirect binding in a Module Environment Record. The String value _N_ is the text of the bound name. _M_ is a Module Record, and _N2_ is a binding that exists in _M_'s Module Environment Record.
-
-
-
-
- GetThisBinding()
-
-
- Return the value of this Environment Record's `this` binding.
-
-
-
-
- The behaviour of the additional concrete specification methods for Module Environment Records are defined by the following algorithms:
+ Module Environment Records support all of the Declarative Environment Record methods listed in
@@ -11225,7 +11371,7 @@
1. Let _M_ and _N2_ be the indirection values provided when this binding for _N_ was created.
1. Let _targetEnv_ be _M_.[[Environment]].
1. If _targetEnv_ is ~empty~, throw a *ReferenceError* exception.
- 1. Return ? _targetEnv_.GetBindingValue (_N2_, *true*).
+ 1. Return ? _targetEnv_.GetBindingValue(_N2_, *true*) .
1. If the binding for _N_ in _envRec_ is an uninitialized binding, throw a *ReferenceError* exception.
1. Return the value currently bound to _N_ in _envRec_.
@@ -11267,20 +11413,18 @@ GetThisBinding ( ): a normal completion containing *undefined*
-
+
CreateImportBinding (
+ _envRec_: a Module Environment Record,
_N_: a String,
_M_: a Module Record,
_N2_: a String,
): ~unused~
- - for
- - a Module Environment Record _envRec_
-
- description
- - It creates a new initialized immutable indirect binding for the name _N_. A binding must not already exist in this Environment Record for _N_. _N2_ is the name of a binding that exists in _M_'s Module Environment Record. Accesses to the value of the new binding will indirectly access the bound value of the target binding.
+ - It creates a new initialized immutable indirect binding for the name _N_. A binding must not already exist in _envRec_ for _N_. _N2_ is the name of a binding that exists in _M_'s Module Environment Record. Accesses to the value of the new binding will indirectly access the bound value of the target binding.
1. Assert: _envRec_ does not already have a binding for _N_.
@@ -11309,12 +11453,11 @@
1. If _env_ is *null*, then
1. Return the Reference Record { [[Base]]: ~unresolvable~, [[ReferencedName]]: _name_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
- 1. Let _exists_ be ? _env_.HasBinding (_name_).
+ 1. Let _exists_ be ? _env_.HasBinding(_name_) .
1. If _exists_ is *true*, then
1. Return the Reference Record { [[Base]]: _env_, [[ReferencedName]]: _name_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
- 1. Else,
- 1. Let _outer_ be _env_.[[OuterEnv]].
- 1. Return ? GetIdentifierReference(_outer_, _name_, _strict_).
+ 1. Let _outer_ be _env_.[[OuterEnv]].
+ 1. Return ? GetIdentifierReference(_outer_, _name_, _strict_).
@@ -11388,7 +11531,6 @@
1. Set _env_.[[ObjectRecord]] to _objRec_.
1. Set _env_.[[GlobalThisValue]] to _thisValue_.
1. Set _env_.[[DeclarativeRecord]] to _dclRec_.
- 1. Set _env_.[[VarNames]] to a new empty List.
1. Set _env_.[[OuterEnv]] to *null*.
1. Return _env_.
@@ -11462,34 +11604,34 @@ PrivateEnvironment Record Operations
NewPrivateEnvironment (
- _outerPrivEnv_: a PrivateEnvironment Record or *null*,
+ _outerPrivateEnv_: a PrivateEnvironment Record or *null*,
): a PrivateEnvironment Record
1. Let _names_ be a new empty List.
- 1. Return the PrivateEnvironment Record { [[OuterPrivateEnvironment]]: _outerPrivEnv_, [[Names]]: _names_ }.
+ 1. Return the PrivateEnvironment Record { [[OuterPrivateEnvironment]]: _outerPrivateEnv_, [[Names]]: _names_ }.
ResolvePrivateIdentifier (
- _privEnv_: a PrivateEnvironment Record,
+ _privateEnv_: a PrivateEnvironment Record,
_identifier_: a String,
): a Private Name
- 1. Let _names_ be _privEnv_.[[Names]].
+ 1. Let _names_ be _privateEnv_.[[Names]].
1. For each Private Name _pn_ of _names_, do
1. If _pn_.[[Description]] is _identifier_, then
1. Return _pn_.
- 1. Let _outerPrivEnv_ be _privEnv_.[[OuterPrivateEnvironment]].
- 1. Assert: _outerPrivEnv_ is not *null*.
- 1. Return ResolvePrivateIdentifier(_outerPrivEnv_, _identifier_).
+ 1. Let _outerPrivateEnv_ be _privateEnv_.[[OuterPrivateEnvironment]].
+ 1. Assert: _outerPrivateEnv_ is not *null*.
+ 1. Return ResolvePrivateIdentifier(_outerPrivateEnv_, _identifier_).
@@ -11501,17 +11643,19 @@ Realms
A realm is represented in this specification as a Realm Record with the fields specified in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[AgentSignifier]]
@@ -11539,7 +11683,7 @@ Realms
[[GlobalObject]]
- an Object or *undefined*
+ an Object
The global object for this realm
@@ -11573,10 +11717,10 @@ Realms
[[LoadedModules]]
- a List of Records with fields [[Specifier]] (a String) and [[Module]] (a Module Record)
+ a List of LoadedModuleRequest Records
- A map from the specifier strings imported by this realm to the resolved Module Record. The list does not contain two different Records with the same [[Specifier]].
+ A map from the specifier strings imported by this realm to the resolved Module Record. The list does not contain two different Records _r1_ and _r2_ such that ModuleRequestsEqual(_r1_, _r2_) is *true*.
As mentioned in HostLoadImportedModule (
@@ -11604,15 +11748,13 @@ InitializeHostDefinedRealm ( ): either a normal completion containing ~unuse
1. Let _realm_ be a new Realm Record.
1. Perform CreateIntrinsics(_realm_).
1. Set _realm_.[[AgentSignifier]] to AgentSignifier().
- 1. Set _realm_.[[GlobalObject]] to *undefined*.
- 1. Set _realm_.[[GlobalEnv]] to *undefined*.
1. Set _realm_.[[TemplateMap]] to a new empty List.
1. Let _newContext_ be a new execution context.
1. Set the Function of _newContext_ to *null*.
1. Set the Realm of _newContext_ to _realm_.
1. Set the ScriptOrModule of _newContext_ to *null*.
1. Push _newContext_ onto the execution context stack; _newContext_ is now the running execution context.
- 1. If the host requires use of an exotic object to serve as _realm_'s global object, then
+ 1. If the host requires use of a specific object to serve as _realm_'s global object, then
1. Let _global_ be such an object created in a host-defined manner.
1. Else,
1. Let _global_ be OrdinaryObjectCreate(_realm_.[[Intrinsics]].[[%Object.prototype%]]).
@@ -11638,7 +11780,7 @@
1. Set _realmRec_.[[Intrinsics]] to a new Record.
- 1. [declared="steps,name,length,slots,prototype"] Set fields of _realmRec_.[[Intrinsics]] with the values listed in
@@ -11670,14 +11812,16 @@ Execution Contexts
An execution context contains whatever implementation specific state is necessary to track the execution progress of its associated code. Each execution context has at least the state components listed in
-
-
- Component
-
-
- Purpose
-
-
+
+
+
+ Component
+
+
+ Purpose
+
+
+
code evaluation state
@@ -11717,14 +11861,16 @@ Execution Contexts
ECMAScript code execution contexts have the additional state components listed in
-
-
- Component
-
-
- Purpose
-
-
+
+
+
+ Component
+
+
+ Purpose
+
+
+
LexicalEnvironment
@@ -11755,14 +11901,16 @@ Execution Contexts
Execution contexts representing the evaluation of Generators have the additional state components listed in
-
-
- Component
-
-
- Purpose
-
-
+
+
+
+ Component
+
+
+ Purpose
+
+
+
Generator
@@ -11786,7 +11934,8 @@ GetActiveScriptOrModule ( ): a Script Record, a Module Record, or *null*
1. If the execution context stack is empty, return *null*.
1. Let _ec_ be the topmost execution context on the execution context stack whose ScriptOrModule component is not *null*.
- 1. If no such execution context exists, return *null*. Otherwise, return _ec_'s ScriptOrModule.
+ 1. If no such execution context exists, return *null*.
+ 1. Return _ec_'s ScriptOrModule.
@@ -11880,7 +12029,7 @@ Jobs and Host Operations to Enqueue Jobs
- At some future point in time, when there is no running context in the agent for which the job is scheduled and that agent's execution context stack is empty, the implementation must:
- Perform any host-defined preparation steps.
- - Invoke the Job Abstract Closure.
+ Invoke the Job Abstract Closure.- Perform any host-defined cleanup steps, after which the execution context stack must be empty.
@@ -11921,17 +12070,19 @@ JobCallback Records
JobCallback Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Callback]]
@@ -12071,15 +12222,17 @@ Agents
An agent signifier is a globally-unique opaque value used to identify an Agent.
-
- Field Name
- Value
- Meaning
-
+
+
+ Field Name
+ Value
+ Meaning
+
+
[[LittleEndian]]
a Boolean
- The default value computed for the isLittleEndian parameter when it is needed by the algorithms GetValueFromBuffer and SetValueInBuffer. The choice is implementation-defined and should be the alternative that is most efficient for the implementation. Once the value has been observed it cannot change.
+ The default value computed for the isLittleEndian parameter when it is needed by the algorithms GetValueFromBuffer and SetValueInBuffer. The choice is implementation-defined and should be the alternative that is most efficient for the implementation.
[[CanBlock]]
@@ -12116,13 +12269,18 @@ Agents
a List of either Objects or Symbols
Initially a new empty List, representing the list of objects and/or symbols to be kept alive until the end of the current Job
+
+ [[ModuleAsyncEvaluationCount]]
+ an integer
+ Initially 0, used to assign unique incrementing values to the [[AsyncEvaluationOrder]] field of modules that are asynchronous or have asynchronous dependencies.
+
- Once the values of [[Signifier]], [[IsLockFree1]], and [[IsLockFree2]] have been observed by any agent in the agent cluster they cannot change.
+ The values of [[LittleEndian]], [[Signifier]], [[IsLockFree1]], [[IsLockFree2]], and [[IsLockFree8]] cannot change.
- The values of [[IsLockFree1]] and [[IsLockFree2]] are not necessarily determined by the hardware, but may also reflect implementation choices that can vary over time and between ECMAScript implementations.
+ The values of [[IsLockFree1]], [[IsLockFree2]], and [[IsLockFree8]] are not necessarily determined by the hardware, but may also reflect implementation choices that can vary over time and between ECMAScript implementations.
There is no [[IsLockFree4]] field: 4-byte atomic operations are always lock-free.
@@ -12157,6 +12315,21 @@ AgentCanSuspend ( ): a Boolean
In some environments it may not be reasonable for a given agent to suspend. For example, in a web browser environment, it may be reasonable to disallow suspending a document's main event handling thread, while still allowing workers' event handling threads to suspend.
+
+
+ IncrementModuleAsyncEvaluationCount ( ): an integer
+
+
+
+ 1. Let _AR_ be the Agent Record of the surrounding agent.
+ 1. Let _count_ be _AR_.[[ModuleAsyncEvaluationCount]].
+ 1. Set _AR_.[[ModuleAsyncEvaluationCount]] to _count_ + 1.
+ 1. Return _count_.
+
+
+ This value is only used to keep track of the relative evaluation order between pending modules. An implementation may unobservably reset [[ModuleAsyncEvaluationCount]] to 0 whenever there are no pending modules.
+
+
@@ -12182,7 +12355,7 @@ Agent Clusters
If different agents within an agent cluster have different values of [[LittleEndian]] it becomes hard to use shared memory for multi-byte data.
- All agents within a cluster must have the same values for the [[IsLockFree1]] field in their respective Agent Records; similarly for the [[IsLockFree2]] field.
+ All agents within a cluster must have the same values for the [[IsLockFree1]] field in their respective Agent Records; similarly for the [[IsLockFree2]] and [[IsLockFree8]] fields.
All agents within a cluster must have different values for the [[Signifier]] field in their respective Agent Records.
@@ -12503,7 +12676,7 @@
1. Return *true*.
- The loop in step
+ The loop in step
@@ -12624,7 +12797,7 @@
- 1. Let _current_ be ? _O_.[[GetOwnProperty]] (_P_).
+ 1. Let _current_ be ? _O_.[[GetOwnProperty]](_P_) .
1. Let _extensible_ be ? IsExtensible(_O_).
1. Return ValidateAndApplyPropertyDescriptor(_O_, _P_, _extensible_, _Desc_, _current_).
@@ -12680,18 +12853,19 @@
1. If _Desc_ has a [[Set]] field and SameValue(_Desc_.[[Set]], _current_.[[Set]]) is *false*, return *false*.
1. Else if _current_.[[Writable]] is *false*, then
1. If _Desc_ has a [[Writable]] field and _Desc_.[[Writable]] is *true*, return *false*.
- 1. If _Desc_ has a [[Value]] field and SameValue(_Desc_.[[Value]], _current_.[[Value]]) is *false*, return *false*.
+ 1. NOTE: SameValue returns *true* for *NaN* values which may be distinguishable by other means. Returning here ensures that any existing property of _O_ remains unmodified.
+ 1. If _Desc_ has a [[Value]] field, return SameValue(_Desc_.[[Value]], _current_.[[Value]]).
1. If _O_ is not *undefined*, then
1. If IsDataDescriptor(_current_) is *true* and IsAccessorDescriptor(_Desc_) is *true*, then
1. If _Desc_ has a [[Configurable]] field, let _configurable_ be _Desc_.[[Configurable]]; else let _configurable_ be _current_.[[Configurable]].
- 1. If _Desc_ has a [[Enumerable]] field, let _enumerable_ be _Desc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
+ 1. If _Desc_ has an [[Enumerable]] field, let _enumerable_ be _Desc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
1. Replace the property named _P_ of object _O_ with an accessor property whose [[Configurable]] and [[Enumerable]] attributes are set to _configurable_ and _enumerable_, respectively, and whose [[Get]] and [[Set]] attributes are set to the value of the corresponding field in _Desc_ if _Desc_ has that field, or to the attribute's default value otherwise.
1. Else if IsAccessorDescriptor(_current_) is *true* and IsDataDescriptor(_Desc_) is *true*, then
1. If _Desc_ has a [[Configurable]] field, let _configurable_ be _Desc_.[[Configurable]]; else let _configurable_ be _current_.[[Configurable]].
- 1. If _Desc_ has a [[Enumerable]] field, let _enumerable_ be _Desc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
+ 1. If _Desc_ has an [[Enumerable]] field, let _enumerable_ be _Desc_.[[Enumerable]]; else let _enumerable_ be _current_.[[Enumerable]].
1. Replace the property named _P_ of object _O_ with a data property whose [[Configurable]] and [[Enumerable]] attributes are set to _configurable_ and _enumerable_, respectively, and whose [[Value]] and [[Writable]] attributes are set to the value of the corresponding field in _Desc_ if _Desc_ has that field, or to the attribute's default value otherwise.
1. Else,
- 1. For each field of _Desc_, set the corresponding attribute of the property named _P_ of object _O_ to the value of the field.
+ 1. For each field name _F_ of _Desc_, set the attribute named _F_ of the property named _P_ of object _O_ to the value of _Desc_'s _F_ field.
1. Return *true*.
@@ -12721,11 +12895,11 @@
- 1. Let _hasOwn_ be ? _O_.[[GetOwnProperty]] (_P_).
+ 1. Let _hasOwn_ be ? _O_.[[GetOwnProperty]](_P_) .
1. If _hasOwn_ is not *undefined*, return *true*.
- 1. Let _parent_ be ? _O_.[[GetPrototypeOf]] ().
+ 1. Let _parent_ be ? _O_.[[GetPrototypeOf]]() .
1. If _parent_ is not *null*, then
- 1. Return ? _parent_.[[HasProperty]] (_P_).
+ 1. Return ? _parent_.[[HasProperty]](_P_) .
1. Return *false*.
@@ -12759,11 +12933,11 @@
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_P_).
+ 1. Let _desc_ be ? _O_.[[GetOwnProperty]](_P_) .
1. If _desc_ is *undefined*, then
- 1. Let _parent_ be ? _O_.[[GetPrototypeOf]] ().
+ 1. Let _parent_ be ? _O_.[[GetPrototypeOf]]() .
1. If _parent_ is *null*, return *undefined*.
- 1. Return ? _parent_.[[Get]] (_P_, _Receiver_).
+ 1. Return ? _parent_.[[Get]](_P_, _Receiver_) .
1. If IsDataDescriptor(_desc_) is *true*, return _desc_.[[Value]].
1. Assert: IsAccessorDescriptor(_desc_) is *true*.
1. Let _getter_ be _desc_.[[Get]].
@@ -12802,7 +12976,7 @@
- 1. Let _ownDesc_ be ? _O_.[[GetOwnProperty]] (_P_).
+ 1. Let _ownDesc_ be ? _O_.[[GetOwnProperty]](_P_) .
1. Return ? OrdinarySetWithOwnDescriptor(_O_, _P_, _V_, _Receiver_, _ownDesc_).
@@ -12822,23 +12996,20 @@
1. If _ownDesc_ is *undefined*, then
- 1. Let _parent_ be ? _O_.[[GetPrototypeOf]] ().
- 1. If _parent_ is not *null*, then
- 1. Return ? _parent_.[[Set]] (_P_, _V_, _Receiver_).
- 1. Else,
- 1. Set _ownDesc_ to the PropertyDescriptor { [[Value]]: *undefined*, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
+ 1. Let _parent_ be ? _O_.[[GetPrototypeOf]]() .
+ 1. If _parent_ is not *null*, return ? _parent_.[[Set]](_P_, _V_, _Receiver_) .
+ 1. Set _ownDesc_ to the PropertyDescriptor { [[Value]]: *undefined*, [[Writable]]: *true*, [[Enumerable]]: *true*, [[Configurable]]: *true* }.
1. If IsDataDescriptor(_ownDesc_) is *true*, then
1. If _ownDesc_.[[Writable]] is *false*, return *false*.
1. If _Receiver_ is not an Object, return *false*.
- 1. Let _existingDescriptor_ be ? _Receiver_.[[GetOwnProperty]] (_P_).
- 1. If _existingDescriptor_ is not *undefined*, then
- 1. If IsAccessorDescriptor(_existingDescriptor_) is *true*, return *false*.
- 1. If _existingDescriptor_.[[Writable]] is *false*, return *false*.
- 1. Let _valueDesc_ be the PropertyDescriptor { [[Value]]: _V_ }.
- 1. Return ? _Receiver_.[[DefineOwnProperty]] (_P_, _valueDesc_).
- 1. Else,
+ 1. Let _existingDescriptor_ be ? _Receiver_.[[GetOwnProperty]](_P_) .
+ 1. If _existingDescriptor_ is *undefined*, then
1. Assert: _Receiver_ does not currently have a property _P_.
1. Return ? CreateDataProperty(_Receiver_, _P_, _V_).
+ 1. If IsAccessorDescriptor(_existingDescriptor_) is *true*, return *false*.
+ 1. If _existingDescriptor_.[[Writable]] is *false*, return *false*.
+ 1. Let _valueDesc_ be the PropertyDescriptor { [[Value]]: _V_ }.
+ 1. Return ? _Receiver_.[[DefineOwnProperty]](_P_, _valueDesc_) .
1. Assert: IsAccessorDescriptor(_ownDesc_) is *true*.
1. Let _setter_ be _ownDesc_.[[Set]].
1. If _setter_ is *undefined*, return *false*.
@@ -12872,7 +13043,7 @@
- 1. Let _desc_ be ? _O_.[[GetOwnProperty]] (_P_).
+ 1. Let _desc_ be ? _O_.[[GetOwnProperty]](_P_) .
1. If _desc_ is *undefined*, return *true*.
1. If _desc_.[[Configurable]] is *true*, then
1. Remove the own property with name _P_ from _O_.
@@ -12941,7 +13112,7 @@
OrdinaryCreateFromConstructor (
- _constructor_: a constructor,
+ _constructor_: a function object,
_intrinsicDefaultProto_: a String,
optional _internalSlotsList_: a List of names of internal slots,
): either a normal completion containing an Object or a throw completion
@@ -13008,17 +13179,19 @@ ECMAScript Function Objects
In addition to [[Extensible]] and [[Prototype]], ECMAScript function objects also have the internal slots listed in
-
-
- Internal Slot
-
-
- Type
-
-
- Description
-
-
+
+
+
+ Internal Slot
+
+
+ Type
+
+
+ Description
+
+
+
[[Environment]]
@@ -13212,8 +13385,8 @@
1. Let _result_ be Completion(OrdinaryCallEvaluateBody(_F_, _argumentsList_)).
1. [id="step-call-pop-context-stack"] Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
1. If _result_ is a return completion, return _result_.[[Value]].
- 1. ReturnIfAbrupt(_result_).
- 1. Return *undefined*.
+ 1. Assert: _result_ is a throw completion.
+ 1. Return ? _result_.
When _calleeContext_ is removed from the execution context stack in step
@@ -13273,7 +13446,7 @@
1. NOTE: ToObject produces wrapper objects using _calleeRealm_.
1. Assert: _localEnv_ is a Function Environment Record.
1. Assert: The next step never returns an abrupt completion because _localEnv_.[[ThisBindingStatus]] is not ~initialized~.
- 1. Perform ! _localEnv_.BindThisValue(_thisValue_).
+ 1. Perform ! BindThisValue(_localEnv_, _thisValue_).
1. Return ~unused~.
@@ -13283,7 +13456,7 @@
Runtime Semantics: EvaluateBody (
_functionObject_: an ECMAScript function object,
_argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ ): a return completion or a throw completion
@@ -13329,7 +13502,7 @@
1. Else,
1. Let _rhs_ be ? Evaluation of |AssignmentExpression|.
1. Let _value_ be ? GetValue(_rhs_).
- 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _value_, [[Target]]: ~empty~ }.
+ 1. Return ReturnCompletion(_value_).
Even though field initializers constitute a function boundary, calling FunctionDeclarationInstantiation does not have any observable effect and so is omitted.
@@ -13348,7 +13521,7 @@
OrdinaryCallEvaluateBody (
_F_: an ECMAScript function object,
_argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ ): a return completion or a throw completion
@@ -13385,12 +13558,12 @@
1. Let _constructorEnv_ be the LexicalEnvironment of _calleeContext_.
1. Let _result_ be Completion(OrdinaryCallEvaluateBody(_F_, _argumentsList_)).
1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
- 1. If _result_ is a return completion, then
- 1. If _result_.[[Value]] is an Object, return _result_.[[Value]].
- 1. If _kind_ is ~base~, return _thisArgument_.
- 1. If _result_.[[Value]] is not *undefined*, throw a *TypeError* exception.
- 1. Else,
- 1. ReturnIfAbrupt(_result_).
+ 1. If _result_ is a throw completion, then
+ 1. Return ? _result_.
+ 1. Assert: _result_ is a return completion.
+ 1. If _result_.[[Value]] is an Object, return _result_.[[Value]].
+ 1. If _kind_ is ~base~, return _thisArgument_.
+ 1. If _result_.[[Value]] is not *undefined*, throw a *TypeError* exception.
1. Let _thisBinding_ be ? _constructorEnv_.GetThisBinding().
1. Assert: _thisBinding_ is an Object.
1. Return _thisBinding_.
@@ -13457,7 +13630,7 @@
1. Return ~unused~.
-
+
%ThrowTypeError% ( )
This function is the %ThrowTypeError% intrinsic object.
It is an anonymous built-in function object that is defined once for each realm.
@@ -13527,6 +13700,7 @@
- It configures _F_ as a method.
+ 1. Assert: _homeObject_ is an ordinary object.
1. Set _F_.[[HomeObject]] to _homeObject_.
1. Return ~unused~.
@@ -13545,13 +13719,11 @@
1. Assert: _homeObject_ is an ordinary, extensible object.
- 1. If _key_ is a Private Name, then
- 1. Return PrivateElement { [[Key]]: _key_, [[Kind]]: ~method~, [[Value]]: _closure_ }.
- 1. Else,
- 1. Let _desc_ be the PropertyDescriptor { [[Value]]: _closure_, [[Writable]]: *true*, [[Enumerable]]: _enumerable_, [[Configurable]]: *true* }.
- 1. Perform ? DefinePropertyOrThrow(_homeObject_, _key_, _desc_).
- 1. NOTE: DefinePropertyOrThrow only returns an abrupt completion when attempting to define a class static method whose _key_ is *"prototype"*.
- 1. Return ~unused~.
+ 1. If _key_ is a Private Name, return PrivateElement { [[Key]]: _key_, [[Kind]]: ~method~, [[Value]]: _closure_ }.
+ 1. Let _desc_ be the PropertyDescriptor { [[Value]]: _closure_, [[Writable]]: *true*, [[Enumerable]]: _enumerable_, [[Configurable]]: *true* }.
+ 1. Perform ? DefinePropertyOrThrow(_homeObject_, _key_, _desc_).
+ 1. NOTE: DefinePropertyOrThrow only returns an abrupt completion when attempting to define a class static method whose _key_ is *"prototype"*.
+ 1. Return ~unused~.
@@ -13570,7 +13742,7 @@
1. Assert: _F_ is an extensible object that does not have a *"name"* own property.
1. If _name_ is a Symbol, then
- 1. Let _description_ be _name_'s [[Description]] value.
+ 1. Let _description_ be _name_.[[Description]].
1. If _description_ is *undefined*, set _name_ to the empty String.
1. Else, set _name_ to the string-concatenation of *"["*, _description_, and *"]"*.
1. Else if _name_ is a Private Name, then
@@ -13580,6 +13752,7 @@
1. If _prefix_ is present, then
1. Set _name_ to the string-concatenation of _prefix_, the code unit 0x0020 (SPACE), and _name_.
1. If _F_ has an [[InitialName]] internal slot, then
+ 1. NOTE: The choice in the following step is made independently each time this Abstract Operation is invoked.
1. Optionally, set _F_.[[InitialName]] to _name_.
1. Perform ! DefinePropertyOrThrow(_F_, *"name"*, PropertyDescriptor { [[Value]]: _name_, [[Writable]]: *false*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Return ~unused~.
@@ -13604,12 +13777,12 @@
-
+
FunctionDeclarationInstantiation (
_func_: an ECMAScript function object,
_argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing ~unused~ or an abrupt completion
+ ): either a normal completion containing ~unused~ or a throw completion
- description
@@ -13619,18 +13792,13 @@
When an execution context is established for evaluating an ECMAScript function a new Function Environment Record is created and bindings for each formal parameter are instantiated in that Environment Record. Each declaration in the function body is also instantiated. If the function's formal parameters do not include any default value initializers then the body declarations are instantiated in the same Environment Record as the parameters. If default value parameter initializers exist, a second Environment Record is created for the body declarations. Formal parameters and functions are initialized as part of FunctionDeclarationInstantiation. All other bindings are initialized during evaluation of the function body.
It performs the following steps when called:
-
1. Let _calleeContext_ be the running execution context.
1. Let _code_ be _func_.[[ECMAScriptCode]].
1. Let _strict_ be _func_.[[Strict]].
1. Let _formals_ be _func_.[[FormalParameters]].
1. Let _parameterNames_ be the BoundNames of _formals_.
- 1. If _parameterNames_ has any duplicate entries, let _hasDuplicates_ be *true*. Otherwise, let _hasDuplicates_ be *false*.
+ 1. If _parameterNames_ has any duplicate entries, let _hasDuplicates_ be *true*; else let _hasDuplicates_ be *false*.
1. Let _simpleParameterList_ be IsSimpleParameterList of _formals_.
1. Let _hasParameterExpressions_ be ContainsExpression of _formals_.
1. Let _varNames_ be the VarDeclaredNames of _code_.
@@ -13688,9 +13856,11 @@
1. Let _parameterBindings_ be _parameterNames_.
1. Let _iteratorRecord_ be CreateListIteratorRecord(_argumentsList_).
1. If _hasDuplicates_ is *true*, then
- 1. Perform ? IteratorBindingInitialization of _formals_ with arguments _iteratorRecord_ and *undefined*.
+ 1. Let _usedEnv_ be *undefined*.
1. Else,
- 1. Perform ? IteratorBindingInitialization of _formals_ with arguments _iteratorRecord_ and _env_.
+ 1. Let _usedEnv_ be _env_.
+ 1. NOTE: The following step cannot return a ReturnCompletion because the only way such a completion can arise in expression position is by use of |YieldExpression|, which is forbidden in parameter lists by Early Error rules in
1. Let _initialValue_ be ! _env_.GetBindingValue(_n_, *false*).
1. Perform ! _varEnv_.InitializeBinding(_n_, _initialValue_).
1. NOTE: A var with the same name as a formal parameter initially has the same value as the corresponding initialized parameter.
- 1. [id="step-functiondeclarationinstantiation-web-compat-insertion-point"] NOTE: Annex
1. Perform ! _varEnv_.SetMutableBinding(_fn_, _fo_, *false*).
1. Return ~unused~.
-
-
-
@@ -13750,6 +13931,7 @@ Built-in Function Objects
- [[Realm]], a Realm Record that represents the realm in which the function was created.
- [[InitialName]], a String that is the initial name of the function. It is used by
+ - [[Async]], a Boolean that indicates whether the function has async function call and construct behaviour in BuiltinCallOrConstruct.
The initial value of a built-in function object's [[Prototype]] internal slot is %Function.prototype%, unless otherwise specified.
A built-in function object must have a [[Call]] internal method that conforms to the definition in
@@ -13784,7 +13966,9 @@
- a built-in function object _F_ (when the method is present)
- 1. Return ? BuiltinCallOrConstruct(_F_, ~uninitialized~, _argumentsList_, _newTarget_).
+ 1. Let _result_ be ? BuiltinCallOrConstruct(_F_, ~uninitialized~, _argumentsList_, _newTarget_).
+ 1. Assert: _result_ is an Object.
+ 1. Return _result_.
@@ -13809,7 +13993,16 @@
1. Set the ScriptOrModule of _calleeContext_ to *null*.
1. Perform any necessary implementation-defined initialization of _calleeContext_.
1. Push _calleeContext_ onto the execution context stack; _calleeContext_ is now the running execution context.
- 1. [id="step-call-builtin-function-result"] Let _result_ be the Completion Record that is the result of evaluating _F_ in a manner that conforms to the specification of _F_. If _thisArgument_ is ~uninitialized~, the *this* value is uninitialized; otherwise, _thisArgument_ provides the *this* value. _argumentsList_ provides the named parameters. _newTarget_ provides the NewTarget value.
+ 1. If _F_.[[Async]] is *true*, then
+ 1. Let _promiseCapability_ be ! NewPromiseCapability(%Promise%).
+ 1. Let _resultsClosure_ be a new Abstract Closure with no parameters that captures _F_, _thisArgument_, _argumentsList_, and _newTarget_ and performs the following steps when called:
+ 1. Let _result_ be the Completion Record that is the result of evaluating _F_ in a manner that conforms to the specification of _F_. If _thisArgument_ is ~uninitialized~, the *this* value is uninitialized; else _thisArgument_ provides the *this* value. _argumentsList_ provides the named parameters. _newTarget_ provides the NewTarget value.
+ 1. NOTE: If _F_ is defined in this document, “the specification of _F_” is the behaviour specified for it via algorithm steps or other means.
+ 1. Return Completion(_result_).
+ 1. Perform AsyncFunctionStart(_promiseCapability_, _resultsClosure_).
+ 1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
+ 1. Return _promiseCapability_.[[Promise]].
+ 1. [id="step-call-builtin-function-result"] Let _result_ be the Completion Record that is the result of evaluating _F_ in a manner that conforms to the specification of _F_. If _thisArgument_ is ~uninitialized~, the *this* value is uninitialized; else _thisArgument_ provides the *this* value. _argumentsList_ provides the named parameters. _newTarget_ provides the NewTarget value.
1. NOTE: If _F_ is defined in this document, “the specification of _F_” is the behaviour specified for it via algorithm steps or other means.
1. Remove _calleeContext_ from the execution context stack and restore _callerContext_ as the running execution context.
1. Return ? _result_.
@@ -13829,7 +14022,8 @@
optional _realm_: a Realm Record,
optional _prototype_: an Object or *null*,
optional _prefix_: a String,
- ): a function object
+ optional _async_: a Boolean,
+ ): a built-in function object
- description
@@ -13838,9 +14032,11 @@
1. If _realm_ is not present, set _realm_ to the current Realm Record.
1. If _prototype_ is not present, set _prototype_ to _realm_.[[Intrinsics]].[[%Function.prototype%]].
+ 1. If _async_ is not present, set _async_ to *false*.
1. Let _internalSlotsList_ be a List containing the names of all the internal slots that Bound Function Exotic Objects
Bound function exotic objects do not have the internal slots of ECMAScript function objects listed in
-
-
- Internal Slot
-
-
- Type
-
-
- Description
-
-
+
+
+
+ Internal Slot
+
+
+ Type
+
+
+ Description
+
+
+
[[BoundTargetFunction]]
@@ -13970,13 +14168,13 @@
- It is used to specify the creation of new bound function exotic objects.
- 1. Let _proto_ be ? _targetFunction_.[[GetPrototypeOf]] ().
+ 1. Let _proto_ be ? _targetFunction_.[[GetPrototypeOf]]() .
1. Let _internalSlotsList_ be the list-concatenation of « [[Prototype]], [[Extensible]] » and the internal slots listed in
- an Array exotic object _A_
- 1. If _P_ is *"length"*, then
- 1. Return ? ArraySetLength(_A_, _Desc_).
- 1. Else if _P_ is an array index, then
+ 1. If _P_ is *"length"*, return ? ArraySetLength(_A_, _Desc_).
+ 1. If _P_ is an array index, then
1. Let _lengthDesc_ be OrdinaryGetOwnProperty(_A_, *"length"*).
+ 1. Assert: _lengthDesc_ is not *undefined*.
1. Assert: IsDataDescriptor(_lengthDesc_) is *true*.
1. Assert: _lengthDesc_.[[Configurable]] is *false*.
1. Let _length_ be _lengthDesc_.[[Value]].
@@ -14067,7 +14265,7 @@
1. If _thisRealm_ and _realmC_ are not the same Realm Record, then
1. If SameValue(_C_, _realmC_.[[Intrinsics]].[[%Array%]]) is *true*, set _C_ to *undefined*.
1. If _C_ is an Object, then
- 1. Set _C_ to ? Get(_C_, @@species).
+ 1. Set _C_ to ? Get(_C_, %Symbol.species%).
1. If _C_ is *null*, set _C_ to *undefined*.
1. If _C_ is *undefined*, return ? ArrayCreate(_length_).
1. If IsConstructor(_C_) is *false*, throw a *TypeError* exception.
@@ -14096,6 +14294,7 @@
1. If SameValueZero(_newLen_, _numberLen_) is *false*, throw a *RangeError* exception.
1. Set _newLenDesc_.[[Value]] to _newLen_.
1. Let _oldLenDesc_ be OrdinaryGetOwnProperty(_A_, *"length"*).
+ 1. Assert: _oldLenDesc_ is not *undefined*.
1. Assert: IsDataDescriptor(_oldLenDesc_) is *true*.
1. Assert: _oldLenDesc_.[[Configurable]] is *false*.
1. Let _oldLen_ be _oldLenDesc_.[[Value]].
@@ -14232,13 +14431,12 @@
1. If _P_ is not a String, return *undefined*.
1. Let _index_ be CanonicalNumericIndexString(_P_).
- 1. If _index_ is *undefined*, return *undefined*.
- 1. If IsIntegralNumber(_index_) is *false*, return *undefined*.
- 1. If _index_ is *-0*𝔽, return *undefined*.
+ 1. If _index_ is not an integral Number, return *undefined*.
+ 1. If _index_ is *-0*𝔽 or _index_ < *-0*𝔽, return *undefined*.
1. Let _str_ be _S_.[[StringData]].
1. Assert: _str_ is a String.
1. Let _len_ be the length of _str_.
- 1. If ℝ(_index_) < 0 or _len_ ≤ ℝ(_index_), return *undefined*.
+ 1. If ℝ(_index_) ≥ _len_, return *undefined*.
1. Let _resultStr_ be the substring of _str_ from ℝ(_index_) to ℝ(_index_) + 1.
1. Return the PropertyDescriptor { [[Value]]: _resultStr_, [[Writable]]: *false*, [[Enumerable]]: *true*, [[Configurable]]: *false* }.
@@ -14256,7 +14454,7 @@ Arguments Exotic Objects
While CreateUnmappedArgumentsObject is grouped into this clause, it creates an ordinary object, not an arguments exotic object.
- Arguments exotic objects have the same internal slots as ordinary objects. They also have a [[ParameterMap]] internal slot. Ordinary arguments objects also have a [[ParameterMap]] internal slot whose value is always undefined. For ordinary argument objects the [[ParameterMap]] internal slot is only used by `Object.prototype.toString` (
+ Arguments exotic objects have the same internal slots as ordinary objects. They also have a [[ParameterMap]] internal slot. Ordinary arguments objects also have a [[ParameterMap]] internal slot whose value is always *undefined*. For ordinary argument objects the [[ParameterMap]] internal slot is only used by `Object.prototype.toString` (
The integer-indexed data properties of an arguments exotic object whose numeric name values are less than the number of formal parameters of the corresponding function object initially share their values with the corresponding argument bindings in the function's execution context. This means that changing the property changes the corresponding value of the argument binding and vice-versa. This correspondence is broken if such a property is deleted and then redefined or if the property is changed into an accessor property. If the arguments object is an ordinary object, the values of its properties are simply a copy of the arguments passed to the function and there is no dynamic linkage between the property values and the formal parameter values.
@@ -14340,11 +14538,9 @@
1. Let _map_ be _args_.[[ParameterMap]].
1. Let _isMapped_ be ! HasOwnProperty(_map_, _P_).
- 1. If _isMapped_ is *false*, then
- 1. Return ? OrdinaryGet(_args_, _P_, _Receiver_).
- 1. Else,
- 1. Assert: _map_ contains a formal parameter mapping for _P_.
- 1. Return ! Get(_map_, _P_).
+ 1. If _isMapped_ is *false*, return ? OrdinaryGet(_args_, _P_, _Receiver_).
+ 1. Assert: _map_ contains a formal parameter mapping for _P_.
+ 1. Return ! Get(_map_, _P_).
@@ -14411,7 +14607,7 @@
1. Let _val_ be _argumentsList_[_index_].
1. Perform ! CreateDataPropertyOrThrow(_obj_, ! ToString(𝔽(_index_)), _val_).
1. Set _index_ to _index_ + 1.
- 1. Perform ! DefinePropertyOrThrow(_obj_, @@iterator, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, %Symbol.iterator%, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Perform ! DefinePropertyOrThrow(_obj_, *"callee"*, PropertyDescriptor { [[Get]]: %ThrowTypeError%, [[Set]]: %ThrowTypeError%, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return _obj_.
@@ -14459,7 +14655,7 @@
1. Let _p_ be MakeArgSetter(_name_, _env_).
1. Perform ! _map_.[[DefineOwnProperty]](! ToString(𝔽(_index_)), PropertyDescriptor { [[Set]]: _p_, [[Get]]: _g_, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Set _index_ to _index_ - 1.
- 1. Perform ! DefinePropertyOrThrow(_obj_, @@iterator, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
+ 1. Perform ! DefinePropertyOrThrow(_obj_, %Symbol.iterator%, PropertyDescriptor { [[Value]]: %Array.prototype.values%, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Perform ! DefinePropertyOrThrow(_obj_, *"callee"*, PropertyDescriptor { [[Value]]: _func_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *true* }).
1. Return _obj_.
@@ -14477,7 +14673,7 @@
1. Let _getterClosure_ be a new Abstract Closure with no parameters that captures _name_ and _env_ and performs the following steps when called:
- 1. Return _env_.GetBindingValue(_name_, *false*).
+ 1. Return NormalCompletion(! _env_.GetBindingValue(_name_, *false*)).
1. Let _getter_ be CreateBuiltinFunction(_getterClosure_, 0, *""*, « »).
1. NOTE: _getter_ is never directly accessible to ECMAScript code.
1. Return _getter_.
@@ -14497,7 +14693,7 @@
1. Let _setterClosure_ be a new Abstract Closure with parameters (_value_) that captures _name_ and _env_ and performs the following steps when called:
- 1. Return ! _env_.SetMutableBinding(_name_, _value_, *false*).
+ 1. Return NormalCompletion(! _env_.SetMutableBinding(_name_, _value_, *false*)).
1. Let _setter_ be CreateBuiltinFunction(_setterClosure_, 1, *""*, « »).
1. NOTE: _setter_ is never directly accessible to ECMAScript code.
1. Return _setter_.
@@ -14508,9 +14704,25 @@
TypedArray Exotic Objects
- A TypedArray is an exotic object that performs special handling of integer index property keys.
- TypedArrays have the same internal slots as ordinary objects and additionally [[ViewedArrayBuffer]], [[ArrayLength]], [[ByteOffset]], [[ContentType]], and [[TypedArrayName]] internal slots.
- An object is a TypedArray if its [[GetOwnProperty]], [[HasProperty]], [[DefineOwnProperty]], [[Get]], [[Set]], [[Delete]], and [[OwnPropertyKeys]] internal methods use the definitions in this section, and its other essential internal methods use the definitions found in
+ A TypedArray is an exotic object that performs special handling of property keys that are canonical numeric strings, using the subset that are in-bounds integer indices to index elements of uniform type and enforcing the invariant that the remainder are absent without incurring prototype chain traversal.
+
+ Because ToString(_n_) for any Number _n_ is a canonical numeric string, an implementation may treat Numbers as property keys for TypedArrays without actually performing the string conversion.
+
+ TypedArrays have the same internal slots as ordinary objects and additionally [[ViewedArrayBuffer]], [[TypedArrayName]], [[ContentType]], [[ByteLength]], [[ByteOffset]], and [[ArrayLength]] internal slots.
+ An object is a TypedArray if its [[PreventExtensions]], [[GetOwnProperty]], [[HasProperty]], [[DefineOwnProperty]], [[Get]], [[Set]], [[Delete]], and [[OwnPropertyKeys]], internal methods use the definitions in this section, and its other essential internal methods use the definitions found in
+
+
+ [[PreventExtensions]] ( ): a normal completion containing a Boolean
+
+ - for
+ - a TypedArray _O_
+
+
+ 1. NOTE: The extensibility-related invariants specified in
+
@@ -14635,7 +14847,8 @@
1. If _P_ is a String, then
1. Let _numericIndex_ be CanonicalNumericIndexString(_P_).
1. If _numericIndex_ is not *undefined*, then
- 1. If IsValidIntegerIndex(_O_, _numericIndex_) is *false*, return *true*; else return *false*.
+ 1. If IsValidIntegerIndex(_O_, _numericIndex_) is *false*, return *true*.
+ 1. Return *false*.
1. Return ! OrdinaryDelete(_O_, _P_).
@@ -14663,21 +14876,23 @@ [[OwnPropertyKeys]] ( ): a normal completion containing a List of property k
TypedArray With Buffer Witness Records
- An TypedArray With Buffer Witness Record is a Record value used to encapsulate a TypedArray along with a cached byte length of the viewed buffer. It is used to help ensure there is a single shared memory read event of the byte length data block when the viewed buffer is a growable SharedArrayBuffer.
+ An TypedArray With Buffer Witness Record is a Record value used to encapsulate a TypedArray along with a cached byte length of the viewed buffer. It is used to help ensure there is a single ReadSharedMemory event of the byte length data block when the viewed buffer is a growable SharedArrayBuffer.
TypedArray With Buffer Witness Records have the fields listed in
-
-
- Field Name
-
-
- Value
-
-
- Meaning
-
-
+
+
+
+ Field Name
+
+
+ Value
+
+
+ Meaning
+
+
+
[[Object]]
@@ -14736,6 +14951,7 @@
1. Let _internalSlotsList_ be « [[Prototype]], [[Extensible]], [[ViewedArrayBuffer]], [[TypedArrayName]], [[ContentType]], [[ByteLength]], [[ByteOffset]], [[ArrayLength]] ».
1. Let _A_ be MakeBasicObject(_internalSlotsList_).
+ 1. Set _A_.[[PreventExtensions]] as specified in
- 1. If IsTypedArrayOutOfBounds(_taRecord_) is *true*, return 0.
- 1. Let _length_ be TypedArrayLength(_taRecord_).
- 1. If _length_ = 0, return 0.
+ 1. Assert: IsTypedArrayOutOfBounds(_taRecord_) is *false*.
1. Let _O_ be _taRecord_.[[Object]].
1. If _O_.[[ByteLength]] is not ~auto~, return _O_.[[ByteLength]].
+ 1. Let _length_ be TypedArrayLength(_taRecord_).
1. Let _elementSize_ be TypedArrayElementSize(_O_).
+ 1. NOTE: The returned byte length is always an integer multiple of _elementSize_, even when the underlying buffer has been resized to a non-integer multiple.
1. Return _length_ × _elementSize_.
@@ -14801,20 +15017,39 @@
1. Let _O_ be _taRecord_.[[Object]].
1. Let _bufferByteLength_ be _taRecord_.[[CachedBufferByteLength]].
- 1. Assert: IsDetachedBuffer(_O_.[[ViewedArrayBuffer]]) is *true* if and only if _bufferByteLength_ is ~detached~.
- 1. If _bufferByteLength_ is ~detached~, return *true*.
+ 1. If IsDetachedBuffer(_O_.[[ViewedArrayBuffer]]) is *true*, then
+ 1. Assert: _bufferByteLength_ is ~detached~.
+ 1. Return *true*.
+ 1. Assert: _bufferByteLength_ is a non-negative integer.
1. Let _byteOffsetStart_ be _O_.[[ByteOffset]].
1. If _O_.[[ArrayLength]] is ~auto~, then
1. Let _byteOffsetEnd_ be _bufferByteLength_.
1. Else,
1. Let _elementSize_ be TypedArrayElementSize(_O_).
- 1. Let _byteOffsetEnd_ be _byteOffsetStart_ + _O_.[[ArrayLength]] × _elementSize_.
+ 1. Let _arrayByteLength_ be _O_.[[ArrayLength]] × _elementSize_.
+ 1. Let _byteOffsetEnd_ be _byteOffsetStart_ + _arrayByteLength_.
+ 1. NOTE: A 0-length TypedArray whose [[ByteOffset]] is _bufferByteLength_ is not considered out-of-bounds.
1. If _byteOffsetStart_ > _bufferByteLength_ or _byteOffsetEnd_ > _bufferByteLength_, return *true*.
- 1. NOTE: 0-length TypedArrays are not considered out-of-bounds.
1. Return *false*.
+
+
+ IsTypedArrayFixedLength (
+ _O_: a TypedArray,
+ ): a Boolean
+
+
+
+
+ 1. If _O_.[[ArrayLength]] is ~auto~, return *false*.
+ 1. Let _buffer_ be _O_.[[ViewedArrayBuffer]].
+ 1. If IsFixedLengthArrayBuffer(_buffer_) is *false* and IsSharedArrayBuffer(_buffer_) is *false*, return *false*.
+ 1. Return *true*.
+
+
+
IsValidIntegerIndex (
@@ -14826,13 +15061,13 @@
1. If IsDetachedBuffer(_O_.[[ViewedArrayBuffer]]) is *true*, return *false*.
- 1. If IsIntegralNumber(_index_) is *false*, return *false*.
- 1. If _index_ is *-0*𝔽, return *false*.
+ 1. If _index_ is not an integral Number, return *false*.
+ 1. If _index_ is *-0*𝔽 or _index_ < *-0*𝔽, return *false*.
1. Let _taRecord_ be MakeTypedArrayWithBufferWitnessRecord(_O_, ~unordered~).
1. NOTE: Bounds checking is not a synchronizing operation when _O_'s backing buffer is a growable SharedArrayBuffer.
1. If IsTypedArrayOutOfBounds(_taRecord_) is *true*, return *false*.
1. Let _length_ be TypedArrayLength(_taRecord_).
- 1. If ℝ(_index_) < 0 or ℝ(_index_) ≥ _length_, return *false*.
+ 1. If ℝ(_index_) ≥ _length_, return *false*.
1. Return *true*.
@@ -14868,7 +15103,7 @@
1. If _O_.[[ContentType]] is ~bigint~, let _numValue_ be ? ToBigInt(_value_).
- 1. Otherwise, let _numValue_ be ? ToNumber(_value_).
+ 1. Else, let _numValue_ be ? ToNumber(_value_).
1. If IsValidIntegerIndex(_O_, _index_) is *true*, then
1. Let _offset_ be _O_.[[ByteOffset]].
1. Let _elementSize_ be TypedArrayElementSize(_O_).
@@ -14909,17 +15144,19 @@ Module Namespace Exotic Objects
Module namespace exotic objects have the internal slots defined in
-
-
- Internal Slot
-
-
- Type
-
-
- Description
-
-
+
+
+
+ Internal Slot
+
+
+ Type
+
+
+ Description
+
+
+
[[Module]]
@@ -15196,7 +15433,7 @@
- 1. Let _current_ be ? _O_.[[GetPrototypeOf]] ().
+ 1. Let _current_ be ? _O_.[[GetPrototypeOf]]() .
1. If SameValue(_V_, _current_) is *true*, return *true*.
1. Return *false*.
@@ -15206,20 +15443,22 @@
Proxy Object Internal Methods and Internal Slots
- A Proxy object is an exotic object whose essential internal methods are partially implemented using ECMAScript code. Every Proxy object has an internal slot called [[ProxyHandler]]. The value of [[ProxyHandler]] is an object, called the proxy's handler object, or *null*. Methods (see
+ A Proxy object is an exotic object whose essential internal methods are partially implemented using ECMAScript code. Every Proxy object has an internal slot called [[ProxyHandler]]. The value of [[ProxyHandler]] is an object, called the proxy's handler object, or *null*. Methods (see
An object is a Proxy exotic object if its essential internal methods (including [[Call]] and [[Construct]], if applicable) use the definitions in this section. These internal methods are installed in ProxyCreate.
-
-
- Internal Method
-
-
- Handler Method
-
-
+
+
+
+ Internal Method
+
+
+ Handler Method
+
+
+
[[GetPrototypeOf]]
@@ -15344,12 +15583,12 @@ [[GetPrototypeOf]] ( ): either a normal completion containing either an Obje
1. Assert: _handler_ is an Object.
1. Let _trap_ be ? GetMethod(_handler_, *"getPrototypeOf"*).
1. If _trap_ is *undefined*, then
- 1. Return ? _target_.[[GetPrototypeOf]] ().
+ 1. Return ? _target_.[[GetPrototypeOf]]() .
1. Let _handlerProto_ be ? Call(_trap_, _handler_, « _target_ »).
1. If _handlerProto_ is not an Object and _handlerProto_ is not *null*, throw a *TypeError* exception.
1. Let _extensibleTarget_ be ? IsExtensible(_target_).
1. If _extensibleTarget_ is *true*, return _handlerProto_.
- 1. Let _targetProto_ be ? _target_.[[GetPrototypeOf]] ().
+ 1. Let _targetProto_ be ? _target_.[[GetPrototypeOf]]() .
1. If SameValue(_handlerProto_, _targetProto_) is *false*, throw a *TypeError* exception.
1. Return _handlerProto_.
@@ -15383,12 +15622,12 @@
1. Assert: _handler_ is an Object.
1. Let _trap_ be ? GetMethod(_handler_, *"setPrototypeOf"*).
1. If _trap_ is *undefined*, then
- 1. Return ? _target_.[[SetPrototypeOf]] (_V_).
+ 1. Return ? _target_.[[SetPrototypeOf]](_V_) .
1. Let _booleanTrapResult_ be ToBoolean(? Call(_trap_, _handler_, « _target_, _V_ »)).
1. If _booleanTrapResult_ is *false*, return *false*.
1. Let _extensibleTarget_ be ? IsExtensible(_target_).
1. If _extensibleTarget_ is *true*, return *true*.
- 1. Let _targetProto_ be ? _target_.[[GetPrototypeOf]] ().
+ 1. Let _targetProto_ be ? _target_.[[GetPrototypeOf]]() .
1. If SameValue(_V_, _targetProto_) is *false*, throw a *TypeError* exception.
1. Return *true*.
@@ -15487,10 +15726,10 @@
1. Assert: _handler_ is an Object.
1. Let _trap_ be ? GetMethod(_handler_, *"getOwnPropertyDescriptor"*).
1. If _trap_ is *undefined*, then
- 1. Return ? _target_.[[GetOwnProperty]] (_P_).
+ 1. Return ? _target_.[[GetOwnProperty]](_P_) .
1. Let _trapResultObj_ be ? Call(_trap_, _handler_, « _target_, _P_ »).
1. If _trapResultObj_ is not an Object and _trapResultObj_ is not *undefined*, throw a *TypeError* exception.
- 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]] (_P_).
+ 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]](_P_) .
1. If _trapResultObj_ is *undefined*, then
1. If _targetDesc_ is *undefined*, return *undefined*.
1. If _targetDesc_.[[Configurable]] is *false*, throw a *TypeError* exception.
@@ -15553,11 +15792,11 @@
1. Assert: _handler_ is an Object.
1. Let _trap_ be ? GetMethod(_handler_, *"defineProperty"*).
1. If _trap_ is *undefined*, then
- 1. Return ? _target_.[[DefineOwnProperty]] (_P_, _Desc_).
+ 1. Return ? _target_.[[DefineOwnProperty]](_P_, _Desc_) .
1. Let _descObj_ be FromPropertyDescriptor(_Desc_).
1. Let _booleanTrapResult_ be ToBoolean(? Call(_trap_, _handler_, « _target_, _P_, _descObj_ »)).
1. If _booleanTrapResult_ is *false*, return *false*.
- 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]] (_P_).
+ 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]](_P_) .
1. Let _extensibleTarget_ be ? IsExtensible(_target_).
1. If _Desc_ has a [[Configurable]] field and _Desc_.[[Configurable]] is *false*, then
1. Let _settingConfigFalse_ be *true*.
@@ -15612,10 +15851,10 @@
1. Assert: _handler_ is an Object.
1. Let _trap_ be ? GetMethod(_handler_, *"has"*).
1. If _trap_ is *undefined*, then
- 1. Return ? _target_.[[HasProperty]] (_P_).
+ 1. Return ? _target_.[[HasProperty]](_P_) .
1. Let _booleanTrapResult_ be ToBoolean(? Call(_trap_, _handler_, « _target_, _P_ »)).
1. If _booleanTrapResult_ is *false*, then
- 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]] (_P_).
+ 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]](_P_) .
1. If _targetDesc_ is not *undefined*, then
1. If _targetDesc_.[[Configurable]] is *false*, throw a *TypeError* exception.
1. Let _extensibleTarget_ be ? IsExtensible(_target_).
@@ -15656,9 +15895,9 @@
1. Assert: _handler_ is an Object.
1. Let _trap_ be ? GetMethod(_handler_, *"get"*).
1. If _trap_ is *undefined*, then
- 1. Return ? _target_.[[Get]] (_P_, _Receiver_).
+ 1. Return ? _target_.[[Get]](_P_, _Receiver_) .
1. Let _trapResult_ be ? Call(_trap_, _handler_, « _target_, _P_, _Receiver_ »).
- 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]] (_P_).
+ 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]](_P_) .
1. If _targetDesc_ is not *undefined* and _targetDesc_.[[Configurable]] is *false*, then
1. If IsDataDescriptor(_targetDesc_) is *true* and _targetDesc_.[[Writable]] is *false*, then
1. If SameValue(_trapResult_, _targetDesc_.[[Value]]) is *false*, throw a *TypeError* exception.
@@ -15698,10 +15937,10 @@
1. Assert: _handler_ is an Object.
1. Let _trap_ be ? GetMethod(_handler_, *"set"*).
1. If _trap_ is *undefined*, then
- 1. Return ? _target_.[[Set]] (_P_, _V_, _Receiver_).
+ 1. Return ? _target_.[[Set]](_P_, _V_, _Receiver_) .
1. Let _booleanTrapResult_ be ToBoolean(? Call(_trap_, _handler_, « _target_, _P_, _V_, _Receiver_ »)).
1. If _booleanTrapResult_ is *false*, return *false*.
- 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]] (_P_).
+ 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]](_P_) .
1. If _targetDesc_ is not *undefined* and _targetDesc_.[[Configurable]] is *false*, then
1. If IsDataDescriptor(_targetDesc_) is *true* and _targetDesc_.[[Writable]] is *false*, then
1. If SameValue(_V_, _targetDesc_.[[Value]]) is *false*, throw a *TypeError* exception.
@@ -15742,10 +15981,10 @@
1. Assert: _handler_ is an Object.
1. Let _trap_ be ? GetMethod(_handler_, *"deleteProperty"*).
1. If _trap_ is *undefined*, then
- 1. Return ? _target_.[[Delete]] (_P_).
+ 1. Return ? _target_.[[Delete]](_P_) .
1. Let _booleanTrapResult_ be ToBoolean(? Call(_trap_, _handler_, « _target_, _P_ »)).
1. If _booleanTrapResult_ is *false*, return *false*.
- 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]] (_P_).
+ 1. Let _targetDesc_ be ? _target_.[[GetOwnProperty]](_P_) .
1. If _targetDesc_ is *undefined*, return *true*.
1. If _targetDesc_.[[Configurable]] is *false*, throw a *TypeError* exception.
1. Let _extensibleTarget_ be ? IsExtensible(_target_).
@@ -15783,7 +16022,7 @@ [[OwnPropertyKeys]] ( ): either a normal completion containing a List of pro
1. If _trap_ is *undefined*, then
1. Return ? _target_.[[OwnPropertyKeys]]() .
1. Let _trapResultArray_ be ? Call(_trap_, _handler_, « _target_ »).
- 1. Let _trapResult_ be ? CreateListFromArrayLike(_trapResultArray_, « String, Symbol »).
+ 1. Let _trapResult_ be ? CreateListFromArrayLike(_trapResultArray_, ~property-key~).
1. If _trapResult_ contains any duplicate entries, throw a *TypeError* exception.
1. Let _extensibleTarget_ be ? IsExtensible(_target_).
1. Let _targetKeys_ be ? _target_.[[OwnPropertyKeys]]() .
@@ -15792,7 +16031,7 @@ [[OwnPropertyKeys]] ( ): either a normal completion containing a List of pro
1. Let _targetConfigurableKeys_ be a new empty List.
1. Let _targetNonconfigurableKeys_ be a new empty List.
1. For each element _key_ of _targetKeys_, do
- 1. Let _desc_ be ? _target_.[[GetOwnProperty]] (_key_).
+ 1. Let _desc_ be ? _target_.[[GetOwnProperty]](_key_) .
1. If _desc_ is not *undefined* and _desc_.[[Configurable]] is *false*, then
1. Append _key_ to _targetNonconfigurableKeys_.
1. Else,
@@ -15820,7 +16059,7 @@ [[OwnPropertyKeys]] ( ): either a normal completion containing a List of pro
The returned List contains no duplicate entries.
-
- The Type of each result List element is either String or Symbol.
+ Each element of the returned List is a property key.
-
The result List must contain the keys of all non-configurable own properties of the target object.
@@ -15956,7 +16195,7 @@
Syntax
The components of a combining character sequence are treated as individual Unicode code points even though a user might think of the whole sequence as a single character.
In string literals, regular expression literals, template literals and identifiers, any Unicode code point may also be expressed using Unicode escape sequences that explicitly express a code point's numeric value. Within a comment, such an escape sequence is effectively ignored as part of the comment.
- ECMAScript differs from the Java programming language in the behaviour of Unicode escape sequences. In a Java program, if the Unicode escape sequence `\\u000A`, for example, occurs within a single-line comment, it is interpreted as a line terminator (Unicode code point U+000A is LINE FEED (LF)) and therefore the next code point is not part of the comment. Similarly, if the Unicode escape sequence `\\u000A` occurs within a string literal in a Java program, it is likewise interpreted as a line terminator, which is not allowed within a string literal—one must write `\\n` instead of `\\u000A` to cause a LINE FEED (LF) to be part of the String value of a string literal. In an ECMAScript program, a Unicode escape sequence occurring within a comment is never interpreted and therefore cannot contribute to termination of the comment. Similarly, a Unicode escape sequence occurring within a string literal in an ECMAScript program always contributes to the literal and is never interpreted as a line terminator or as a code point that might terminate the string literal.
+ ECMAScript differs from the Java programming language in the behaviour of Unicode escape sequences. In a Java program, if the Unicode escape sequence `\\u000A`, for example, occurs within a single-line comment, it is interpreted as a line terminator (Unicode code point U+000A is LINE FEED (LF)) and therefore the next code point is not part of the comment. Similarly, if the Unicode escape sequence `\\u000A` occurs within a string literal in a Java program, it is likewise interpreted as a line terminator, which is not allowed within a string literal—one must write `\\n` instead of `\\u000A` to cause a LINE FEED (LF) to be part of the value of a string literal. In an ECMAScript program, a Unicode escape sequence occurring within a comment is never interpreted and therefore cannot contribute to termination of the comment. Similarly, a Unicode escape sequence occurring within a string literal in an ECMAScript program always contributes to the literal and is never interpreted as a line terminator or as a code point that might terminate the string literal.
@@ -16075,7 +16314,7 @@
1. If _sourceText_ is a String, set _sourceText_ to StringToCodePoints(_sourceText_).
1. Attempt to parse _sourceText_ using _goalSymbol_ as the goal symbol, and analyse the parse result for any early error conditions. Parsing and early error detection may be interleaved in an implementation-defined manner.
1. If the parse succeeded and no early errors were found, return the Parse Node (an instance of _goalSymbol_) at the root of the parse tree resulting from the parse.
- 1. Otherwise, return a List of one or more *SyntaxError* objects representing the parsing errors and/or early errors. If more than one parsing error or early error is present, the number and ordering of error objects in the list is implementation-defined, but at least one must be present.
+ 1. Return a List of one or more *SyntaxError* objects representing the parsing errors and/or early errors. If more than one parsing error or early error is present, the number and ordering of error objects in the list is implementation-defined, but at least one must be present.
Consider a text that has an early error at a particular point, and also a syntax error at a later point. An implementation that does a parse pass followed by an early errors pass might report the syntax error and not proceed to the early errors pass. An implementation that interleaves the two activities might report the early error and not proceed to find the syntax error. A third implementation might report both errors. All of these behaviours are conformant.
@@ -16112,7 +16351,7 @@ Types of Source Code
- Function code is generally provided as the bodies of Function Definitions (
+ Function code is generally provided as the bodies of Function Definitions (
The practical effect of including the |BindingIdentifier| in function code is that the Early Errors for strict mode code are applied to a |BindingIdentifier| that is the name of a function whose body contains a "use strict" directive, even if the surrounding code is not strict mode code.
@@ -16162,7 +16401,8 @@
- 1. If the source text matched by _node_ is strict mode code, return *true*; else return *false*.
+ 1. If the source text matched by _node_ is strict mode code, return *true*.
+ 1. Return *false*.
@@ -16245,17 +16485,19 @@ White Space
The ECMAScript white space code points are listed in
-
-
- Code Points
-
-
- Name
-
-
- Abbreviation
-
-
+
+
+
+ Code Points
+
+
+ Name
+
+
+ Abbreviation
+
+
+
`U+0009`
@@ -16337,17 +16579,19 @@ Line Terminators
The ECMAScript line terminator code points are listed in
-
-
- Code Point
-
-
- Unicode Name
-
-
- Abbreviation
-
-
+
+
+
+ Code Point
+
+
+ Unicode Name
+
+
+ Abbreviation
+
+
+
`U+000A`
@@ -17166,20 +17410,22 @@ Static Semantics: SV ( ): a String
-
-
- Escape Sequence
-
-
- Code Unit Value
-
-
- Unicode Character Name
-
-
- Symbol
-
-
+
+
+
+ Escape Sequence
+
+
+ Code Unit Value
+
+
+ Unicode Character Name
+
+
+ Symbol
+
+
+
`\\b`
@@ -18261,7 +18507,7 @@
ElementList : ElementList `,` Elision? AssignmentExpression
- 1. Set _nextIndex_ to ? ArrayAccumulation of |ElementList| with arguments _array_ and _nextIndex_.
+ 1. Set _nextIndex_ to ? ArrayAccumulation of the derived |ElementList| with arguments _array_ and _nextIndex_.
1. If |Elision| is present, then
1. Set _nextIndex_ to ? ArrayAccumulation of |Elision| with arguments _array_ and _nextIndex_.
1. Let _initResult_ be ? Evaluation of |AssignmentExpression|.
@@ -18271,7 +18517,7 @@
ElementList : ElementList `,` Elision? SpreadElement
- 1. Set _nextIndex_ to ? ArrayAccumulation of |ElementList| with arguments _array_ and _nextIndex_.
+ 1. Set _nextIndex_ to ? ArrayAccumulation of the derived |ElementList| with arguments _array_ and _nextIndex_.
1. If |Elision| is present, then
1. Set _nextIndex_ to ? ArrayAccumulation of |Elision| with arguments _array_ and _nextIndex_.
1. Return ? ArrayAccumulation of |SpreadElement| with arguments _array_ and _nextIndex_.
@@ -18394,7 +18640,7 @@ Static Semantics: Early Errors
-
- It is a Syntax Error if the PropertyNameList of |PropertyDefinitionList| contains any duplicate entries for *"__proto__"* and at least two of those entries were obtained from productions of the form
PropertyDefinition : PropertyName `:` AssignmentExpression . This rule is not applied if this |ObjectLiteral| is contained within a |Script| that is being parsed for JSON.parse (see step JSON.parse ).
+ It is a Syntax Error if the PropertyNameList of |PropertyDefinitionList| contains any duplicate entries for *"__proto__"* and at least two of those entries were obtained from productions of the form PropertyDefinition : PropertyName `:` AssignmentExpression . This rule is not applied if this |ObjectLiteral| is contained within a |Script| that is being parsed for ParseJSON (see step
@@ -18416,6 +18662,28 @@ Static Semantics: IsComputedPropertyKey ( ): a Boolean
+
+ Static Semantics: PropertyDefinitionNodes ( ): a List of Parse Nodes
+
+
+
+ ObjectLiteral : `{` `}`
+
+ 1. Return a new empty List.
+
+
+ PropertyDefinitionList : PropertyDefinition
+
+ 1. Return « |PropertyDefinition| ».
+
+
+ PropertyDefinitionList : PropertyDefinitionList `,` PropertyDefinition
+
+ 1. Let _head_ be the PropertyDefinitionNodes of the derived |PropertyDefinitionList|.
+ 1. Return the list-concatenation of _head_ and « |PropertyDefinition| ».
+
+
+
Static Semantics: PropertyNameList ( ): a List of Strings
@@ -18506,7 +18774,7 @@
PropertyDefinition : PropertyName `:` AssignmentExpression
1. Let _propKey_ be ? Evaluation of |PropertyName|.
- 1. If this |PropertyDefinition| is contained within a |Script| that is being evaluated for JSON.parse (see step JSON.parse ), then
+ 1. If this |PropertyDefinition| is contained within a |Script| that is being evaluated for ParseJSON (see step
1. Let _propValue_ be ? GetValue(_exprValueRef_).
1. If _isProtoSetter_ is *true*, then
1. If _propValue_ is an Object or _propValue_ is *null*, then
- 1. Perform ! _object_.[[SetPrototypeOf]] (_propValue_).
+ 1. Perform ! _object_.[[SetPrototypeOf]](_propValue_) .
1. Return ~unused~.
1. Assert: _object_ is an ordinary, extensible object with no non-configurable properties.
1. Perform ! CreateDataPropertyOrThrow(_object_, _propKey_, _propValue_).
@@ -18577,7 +18845,8 @@
1. Let _stringValue_ be CodePointsToString(_patternText_).
1. Set _patternText_ to the sequence of code points resulting from interpreting each of the 16-bit elements of _stringValue_ as a Unicode BMP code point. UTF-16 decoding is not applied to the elements.
1. Let _parseResult_ be ParsePattern(_patternText_, _u_, _v_).
- 1. If _parseResult_ is a Parse Node, return *true*; else return *false*.
+ 1. If _parseResult_ is a Parse Node, return *true*.
+ 1. Return *false*.
@@ -18927,7 +19196,8 @@ Syntax
`super` Arguments[?Yield, ?Await]
ImportCall[Yield, Await] :
- `import` `(` AssignmentExpression[+In, ?Yield, ?Await] `)`
+ `import` `(` AssignmentExpression[+In, ?Yield, ?Await] `,`? `)`
+ `import` `(` AssignmentExpression[+In, ?Yield, ?Await] `,` AssignmentExpression[+In, ?Yield, ?Await] `,`? `)`
Arguments[Yield, Await] :
`(` `)`
@@ -19106,8 +19376,8 @@
1. Let _propertyNameReference_ be ? Evaluation of _expression_.
1. Let _propertyNameValue_ be ? GetValue(_propertyNameReference_).
- 1. Let _propertyKey_ be ? ToPropertyKey(_propertyNameValue_).
- 1. Return the Reference Record { [[Base]]: _baseValue_, [[ReferencedName]]: _propertyKey_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
+ 1. NOTE: In most cases, ToPropertyKey will be performed on _propertyNameValue_ immediately after this step. However, in the case of `a[b] = c`, it will not be performed until after evaluation of `c`.
+ 1. Return the Reference Record { [[Base]]: _baseValue_, [[ReferencedName]]: _propertyNameValue_, [[Strict]]: _strict_, [[ThisValue]]: ~empty~ }.
@@ -19181,7 +19451,7 @@ Runtime Semantics: Evaluation
1. Let _argList_ be ? ArgumentListEvaluation of _arguments_.
1. If _argList_ has no elements, return *undefined*.
1. Let _evalArg_ be the first element of _argList_.
- 1. If IsStrict(this |CallExpression|) is *true*, let _strictCaller_ be *true*. Otherwise let _strictCaller_ be *false*.
+ 1. If IsStrict(this |CallExpression|) is *true*, let _strictCaller_ be *true*; else let _strictCaller_ be *false*.
1. [id="step-callexpression-evaluation-direct-eval"] Return ? PerformEval(_evalArg_, _strictCaller_, *true*).
1. Let _thisCall_ be this |CallExpression|.
1. Let _tailCall_ be IsInTailPosition(_thisCall_).
@@ -19239,9 +19509,9 @@ Runtime Semantics: Evaluation
1. Let _actualThis_ be ? _env_.GetThisBinding().
1. Let _propertyNameReference_ be ? Evaluation of |Expression|.
1. Let _propertyNameValue_ be ? GetValue(_propertyNameReference_).
- 1. Let _propertyKey_ be ? ToPropertyKey(_propertyNameValue_).
1. Let _strict_ be IsStrict(this |SuperProperty|).
- 1. Return ? MakeSuperPropertyReference(_actualThis_, _propertyKey_, _strict_).
+ 1. NOTE: In most cases, ToPropertyKey will be performed on _propertyNameValue_ immediately after this step. However, in the case of `super[b] = c`, it will not be performed until after evaluation of `c`.
+ 1. Return MakeSuperPropertyReference(_actualThis_, _propertyNameValue_, _strict_).
SuperProperty : `super` `.` IdentifierName
@@ -19249,18 +19519,19 @@ Runtime Semantics: Evaluation
1. Let _actualThis_ be ? _env_.GetThisBinding().
1. Let _propertyKey_ be the StringValue of |IdentifierName|.
1. Let _strict_ be IsStrict(this |SuperProperty|).
- 1. Return ? MakeSuperPropertyReference(_actualThis_, _propertyKey_, _strict_).
+ 1. Return MakeSuperPropertyReference(_actualThis_, _propertyKey_, _strict_).
SuperCall : `super` Arguments
1. Let _newTarget_ be GetNewTarget().
- 1. Assert: _newTarget_ is an Object.
+ 1. Assert: _newTarget_ is a constructor.
1. Let _func_ be GetSuperConstructor().
1. Let _argList_ be ? ArgumentListEvaluation of |Arguments|.
1. If IsConstructor(_func_) is *false*, throw a *TypeError* exception.
1. Let _result_ be ? Construct(_func_, _argList_, _newTarget_).
1. Let _thisER_ be GetThisEnvironment().
- 1. Perform ? _thisER_.BindThisValue(_result_).
+ 1. Assert: _thisER_ is a Function Environment Record.
+ 1. Perform ? BindThisValue(_thisER_, _result_).
1. Let _F_ be _thisER_.[[FunctionObject]].
1. Assert: _F_ is an ECMAScript function object.
1. Perform ? InitializeInstanceElements(_result_, _F_).
@@ -19286,16 +19557,17 @@ GetSuperConstructor ( ): an ECMAScript language value
MakeSuperPropertyReference (
_actualThis_: an ECMAScript language value,
- _propertyKey_: a property key,
+ _propertyKey_: an ECMAScript language value,
_strict_: a Boolean,
- ): either a normal completion containing a Super Reference Record or a throw completion
+ ): a Super Reference Record
1. Let _env_ be GetThisEnvironment().
1. Assert: _env_.HasSuperBinding() is *true*.
- 1. Let _baseValue_ be ? _env_.GetSuperBase().
+ 1. Assert: _env_ is a Function Environment Record.
+ 1. Let _baseValue_ be GetSuperBase(_env_).
1. Return the Reference Record { [[Base]]: _baseValue_, [[ReferencedName]]: _propertyKey_, [[Strict]]: _strict_, [[ThisValue]]: _actualThis_ }.
@@ -19486,58 +19758,108 @@ Import Calls
Runtime Semantics: Evaluation
- ImportCall : `import` `(` AssignmentExpression `)`
+ ImportCall : `import` `(` AssignmentExpression `,`? `)`
+
+ 1. Return ? EvaluateImportCall(|AssignmentExpression|).
+
+
+ ImportCall : `import` `(` AssignmentExpression `,` AssignmentExpression `,`? `)`
+
+ 1. Return ? EvaluateImportCall(the first |AssignmentExpression|, the second |AssignmentExpression|).
+
+
+
+
+
+ EvaluateImportCall (
+ _specifierExpression_: a Parse Node,
+ optional _optionsExpression_: a Parse Node,
+ ): either a normal completion containing a Promise or an abrupt completion
+
+
+
1. Let _referrer_ be GetActiveScriptOrModule().
1. If _referrer_ is *null*, set _referrer_ to the current Realm Record.
- 1. Let _argRef_ be ? Evaluation of |AssignmentExpression|.
- 1. Let _specifier_ be ? GetValue(_argRef_).
+ 1. Let _specifierRef_ be ? Evaluation of _specifierExpression_.
+ 1. Let _specifier_ be ? GetValue(_specifierRef_).
+ 1. If _optionsExpression_ is present, then
+ 1. Let _optionsRef_ be ? Evaluation of _optionsExpression_.
+ 1. Let _options_ be ? GetValue(_optionsRef_).
+ 1. Else,
+ 1. Let _options_ be *undefined*.
1. Let _promiseCapability_ be ! NewPromiseCapability(%Promise%).
1. Let _specifierString_ be Completion(ToString(_specifier_)).
1. IfAbruptRejectPromise(_specifierString_, _promiseCapability_).
- 1. Perform HostLoadImportedModule(_referrer_, _specifierString_, ~empty~, _promiseCapability_).
+ 1. Let _attributes_ be a new empty List.
+ 1. If _options_ is not *undefined*, then
+ 1. If _options_ is not an Object, then
+ 1. Perform ! Call(_promiseCapability_.[[Reject]], *undefined*, « a newly created *TypeError* object »).
+ 1. Return _promiseCapability_.[[Promise]].
+ 1. Let _attributesObj_ be Completion(Get(_options_, *"with"*)).
+ 1. IfAbruptRejectPromise(_attributesObj_, _promiseCapability_).
+ 1. If _attributesObj_ is not *undefined*, then
+ 1. If _attributesObj_ is not an Object, then
+ 1. Perform ! Call(_promiseCapability_.[[Reject]], *undefined*, « a newly created *TypeError* object »).
+ 1. Return _promiseCapability_.[[Promise]].
+ 1. Let _entries_ be Completion(EnumerableOwnProperties(_attributesObj_, ~key+value~)).
+ 1. IfAbruptRejectPromise(_entries_, _promiseCapability_).
+ 1. For each element _entry_ of _entries_, do
+ 1. Let _key_ be ! Get(_entry_, *"0"*).
+ 1. Let _value_ be ! Get(_entry_, *"1"*).
+ 1. If _key_ is a String, then
+ 1. If _value_ is not a String, then
+ 1. Perform ! Call(_promiseCapability_.[[Reject]], *undefined*, « a newly created *TypeError* object »).
+ 1. Return _promiseCapability_.[[Promise]].
+ 1. Append the ImportAttribute Record { [[Key]]: _key_, [[Value]]: _value_ } to _attributes_.
+ 1. If AllImportAttributesSupported(_attributes_) is *false*, then
+ 1. Perform ! Call(_promiseCapability_.[[Reject]], *undefined*, « a newly created *TypeError* object »).
+ 1. Return _promiseCapability_.[[Promise]].
+ 1. Sort _attributes_ according to the lexicographic order of their [[Key]] field, treating the value of each such field as a sequence of UTF-16 code unit values. NOTE: This sorting is observable only in that hosts are prohibited from changing behaviour based on the order in which attributes are enumerated.
+ 1. Let _moduleRequest_ be a new ModuleRequest Record { [[Specifier]]: _specifierString_, [[Attributes]]: _attributes_ }.
+ 1. Perform HostLoadImportedModule(_referrer_, _moduleRequest_, ~empty~, _promiseCapability_).
1. Return _promiseCapability_.[[Promise]].
+
-
-
- ContinueDynamicImport (
- _promiseCapability_: a PromiseCapability Record,
- _moduleCompletion_: either a normal completion containing a Module Record or a throw completion,
- ): ~unused~
-
-
- - description
- - It completes the process of a dynamic import originally started by an
`import()` call, resolving or rejecting the promise returned by that call as appropriate.
-
-
- 1. If _moduleCompletion_ is an abrupt completion, then
- 1. Perform ! Call(_promiseCapability_.[[Reject]], *undefined*, « _moduleCompletion_.[[Value]] »).
- 1. Return ~unused~.
- 1. Let _module_ be _moduleCompletion_.[[Value]].
- 1. Let _loadPromise_ be _module_.LoadRequestedModules().
- 1. Let _rejectedClosure_ be a new Abstract Closure with parameters (_reason_) that captures _promiseCapability_ and performs the following steps when called:
- 1. Perform ! Call(_promiseCapability_.[[Reject]], *undefined*, « _reason_ »).
- 1. Return ~unused~.
- 1. Let _onRejected_ be CreateBuiltinFunction(_rejectedClosure_, 1, *""*, « »).
- 1. Let _linkAndEvaluateClosure_ be a new Abstract Closure with no parameters that captures _module_, _promiseCapability_, and _onRejected_ and performs the following steps when called:
- 1. Let _link_ be Completion(_module_.Link()).
- 1. If _link_ is an abrupt completion, then
- 1. Perform ! Call(_promiseCapability_.[[Reject]], *undefined*, « _link_.[[Value]] »).
- 1. Return ~unused~.
- 1. Let _evaluatePromise_ be _module_.Evaluate().
- 1. Let _fulfilledClosure_ be a new Abstract Closure with no parameters that captures _module_ and _promiseCapability_ and performs the following steps when called:
- 1. Let _namespace_ be GetModuleNamespace(_module_).
- 1. Perform ! Call(_promiseCapability_.[[Resolve]], *undefined*, « _namespace_ »).
- 1. Return ~unused~.
- 1. Let _onFulfilled_ be CreateBuiltinFunction(_fulfilledClosure_, 0, *""*, « »).
- 1. Perform PerformPromiseThen(_evaluatePromise_, _onFulfilled_, _onRejected_).
- 1. Return ~unused~.
- 1. Let _linkAndEvaluate_ be CreateBuiltinFunction(_linkAndEvaluateClosure_, 0, *""*, « »).
- 1. Perform PerformPromiseThen(_loadPromise_, _linkAndEvaluate_, _onRejected_).
+
+
+ ContinueDynamicImport (
+ _promiseCapability_: a PromiseCapability Record,
+ _moduleCompletion_: either a normal completion containing a Module Record or a throw completion,
+ ): ~unused~
+
+
+ - description
+ - It completes the process of a dynamic import originally started by an
`import()` call, resolving or rejecting the promise returned by that call as appropriate.
+
+
+ 1. If _moduleCompletion_ is an abrupt completion, then
+ 1. Perform ! Call(_promiseCapability_.[[Reject]], *undefined*, « _moduleCompletion_.[[Value]] »).
1. Return ~unused~.
-
-
+ 1. Let _module_ be _moduleCompletion_.[[Value]].
+ 1. Let _loadPromise_ be _module_.LoadRequestedModules().
+ 1. Let _rejectedClosure_ be a new Abstract Closure with parameters (_reason_) that captures _promiseCapability_ and performs the following steps when called:
+ 1. Perform ! Call(_promiseCapability_.[[Reject]], *undefined*, « _reason_ »).
+ 1. Return NormalCompletion(*undefined*).
+ 1. Let _onRejected_ be CreateBuiltinFunction(_rejectedClosure_, 1, *""*, « »).
+ 1. Let _linkAndEvaluateClosure_ be a new Abstract Closure with no parameters that captures _module_, _promiseCapability_, and _onRejected_ and performs the following steps when called:
+ 1. Let _link_ be Completion(_module_.Link()).
+ 1. If _link_ is an abrupt completion, then
+ 1. Perform ! Call(_promiseCapability_.[[Reject]], *undefined*, « _link_.[[Value]] »).
+ 1. Return NormalCompletion(*undefined*).
+ 1. Let _evaluatePromise_ be _module_.Evaluate().
+ 1. Let _fulfilledClosure_ be a new Abstract Closure with no parameters that captures _module_ and _promiseCapability_ and performs the following steps when called:
+ 1. Let _namespace_ be GetModuleNamespace(_module_).
+ 1. Perform ! Call(_promiseCapability_.[[Resolve]], *undefined*, « _namespace_ ») .
+ 1. Return NormalCompletion(*undefined*).
+ 1. Let _onFulfilled_ be CreateBuiltinFunction(_fulfilledClosure_, 0, *""*, « »).
+ 1. Perform PerformPromiseThen(_evaluatePromise_, _onFulfilled_, _onRejected_).
+ 1. Return ~unused~.
+ 1. Let _linkAndEvaluate_ be CreateBuiltinFunction(_linkAndEvaluateClosure_, 0, *""*, « »).
+ 1. Perform PerformPromiseThen(_loadPromise_, _linkAndEvaluate_, _onRejected_).
+ 1. Return ~unused~.
+
@@ -19591,9 +19913,8 @@ Runtime Semantics: Evaluation
1. Perform HostFinalizeImportMeta(_importMeta_, _module_).
1. Set _module_.[[ImportMeta]] to _importMeta_.
1. Return _importMeta_.
- 1. Else,
- 1. Assert: _importMeta_ is an Object.
- 1. Return _importMeta_.
+ 1. Assert: _importMeta_ is an Object.
+ 1. Return _importMeta_.
@@ -19651,7 +19972,7 @@ Static Semantics: Early Errors
-
- It is an early Syntax Error if the AssignmentTargetType of |LeftHandSideExpression| is not ~simple~.
+ It is an early Syntax Error if the AssignmentTargetType of |LeftHandSideExpression| is ~invalid~.
@@ -19662,7 +19983,7 @@ Static Semantics: Early Errors
-
- It is an early Syntax Error if the AssignmentTargetType of |UnaryExpression| is not ~simple~.
+ It is an early Syntax Error if the AssignmentTargetType of |UnaryExpression| is ~invalid~.
@@ -19675,6 +19996,7 @@ Runtime Semantics: Evaluation
UpdateExpression : LeftHandSideExpression `++`
1. Let _lhs_ be ? Evaluation of |LeftHandSideExpression|.
+ 1. If the AssignmentTargetType of |LeftHandSideExpression| is ~web-compat~, throw a *ReferenceError* exception.
1. Let _oldValue_ be ? ToNumeric(? GetValue(_lhs_)).
1. If _oldValue_ is a Number, then
1. Let _newValue_ be Number::add(_oldValue_, *1*𝔽).
@@ -19695,6 +20017,7 @@ Runtime Semantics: Evaluation
UpdateExpression : LeftHandSideExpression `--`
1. Let _lhs_ be ? Evaluation of |LeftHandSideExpression|.
+ 1. If the AssignmentTargetType of |LeftHandSideExpression| is ~web-compat~, throw a *ReferenceError* exception.
1. Let _oldValue_ be ? ToNumeric(? GetValue(_lhs_)).
1. If _oldValue_ is a Number, then
1. Let _newValue_ be Number::subtract(_oldValue_, *1*𝔽).
@@ -19715,6 +20038,7 @@ Runtime Semantics: Evaluation
UpdateExpression : `++` UnaryExpression
1. Let _expr_ be ? Evaluation of |UnaryExpression|.
+ 1. If the AssignmentTargetType of |UnaryExpression| is ~web-compat~, throw a *ReferenceError* exception.
1. Let _oldValue_ be ? ToNumeric(? GetValue(_expr_)).
1. If _oldValue_ is a Number, then
1. Let _newValue_ be Number::add(_oldValue_, *1*𝔽).
@@ -19735,6 +20059,7 @@ Runtime Semantics: Evaluation
UpdateExpression : `--` UnaryExpression
1. Let _expr_ be ? Evaluation of |UnaryExpression|.
+ 1. If the AssignmentTargetType of |UnaryExpression| is ~web-compat~, throw a *ReferenceError* exception.
1. Let _oldValue_ be ? ToNumeric(? GetValue(_expr_)).
1. If _oldValue_ is a Number, then
1. Let _newValue_ be Number::subtract(_oldValue_, *1*𝔽).
@@ -19800,13 +20125,14 @@ Runtime Semantics: Evaluation
1. Assert: IsPrivateReference(_ref_) is *false*.
1. If IsSuperReference(_ref_) is *true*, throw a *ReferenceError* exception.
1. [id="step-delete-operator-toobject"] Let _baseObj_ be ? ToObject(_ref_.[[Base]]).
- 1. Let _deleteStatus_ be ? _baseObj_.[[Delete]] (_ref_.[[ReferencedName]]).
+ 1. If _ref_.[[ReferencedName]] is not a property key, then
+ 1. Set _ref_.[[ReferencedName]] to ? ToPropertyKey(_ref_.[[ReferencedName]]).
+ 1. Let _deleteStatus_ be ? _baseObj_.[[Delete]](_ref_.[[ReferencedName]]) .
1. If _deleteStatus_ is *false* and _ref_.[[Strict]] is *true*, throw a *TypeError* exception.
1. Return _deleteStatus_.
- 1. Else,
- 1. Let _base_ be _ref_.[[Base]].
- 1. Assert: _base_ is an Environment Record.
- 1. Return ? _base_.DeleteBinding (_ref_.[[ReferencedName]]).
+ 1. Let _base_ be _ref_.[[Base]].
+ 1. Assert: _base_ is an Environment Record.
+ 1. Return ? _base_.DeleteBinding(_ref_.[[ReferencedName]]) .
When a `delete` operator occurs within strict mode code, a *SyntaxError* exception is thrown if its |UnaryExpression| is a direct reference to a variable, function argument, or function name. In addition, if a `delete` operator occurs within strict mode code and the property to be deleted has the attribute { [[Configurable]]: *false* } (or otherwise cannot be deleted), a *TypeError* exception is thrown.
@@ -19837,7 +20163,7 @@ Runtime Semantics: Evaluation
The `typeof` Operator
-
+
Runtime Semantics: Evaluation
UnaryExpression : `typeof` UnaryExpression
@@ -19853,8 +20179,9 @@ Runtime Semantics: Evaluation
1. If _val_ is a Number, return *"number"*.
1. If _val_ is a BigInt, return *"bigint"*.
1. Assert: _val_ is an Object.
- 1. [id="step-typeof-web-compat-insertion-point"] NOTE: This step is replaced in section
@@ -19888,11 +20215,9 @@ Runtime Semantics: Evaluation
1. Let _expr_ be ? Evaluation of |UnaryExpression|.
1. Let _oldValue_ be ? ToNumeric(? GetValue(_expr_)).
- 1. If _oldValue_ is a Number, then
- 1. Return Number::unaryMinus(_oldValue_).
- 1. Else,
- 1. Assert: _oldValue_ is a BigInt.
- 1. Return BigInt::unaryMinus(_oldValue_).
+ 1. If _oldValue_ is a Number, return Number::unaryMinus(_oldValue_).
+ 1. Assert: _oldValue_ is a BigInt.
+ 1. Return BigInt::unaryMinus(_oldValue_).
@@ -19906,11 +20231,9 @@ Runtime Semantics: Evaluation
1. Let _expr_ be ? Evaluation of |UnaryExpression|.
1. Let _oldValue_ be ? ToNumeric(? GetValue(_expr_)).
- 1. If _oldValue_ is a Number, then
- 1. Return Number::bitwiseNOT(_oldValue_).
- 1. Else,
- 1. Assert: _oldValue_ is a BigInt.
- 1. Return BigInt::bitwiseNOT(_oldValue_).
+ 1. If _oldValue_ is a Number, return Number::bitwiseNOT(_oldValue_).
+ 1. Assert: _oldValue_ is a BigInt.
+ 1. Return BigInt::bitwiseNOT(_oldValue_).
@@ -20104,67 +20427,72 @@ Syntax
Runtime Semantics: Evaluation
RelationalExpression : RelationalExpression `<` ShiftExpression
- 1. Let _lref_ be ? Evaluation of |RelationalExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |ShiftExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Let _r_ be ? IsLessThan(_lval_, _rval_, *true*).
- 1. If _r_ is *undefined*, return *false*. Otherwise, return _r_.
+ 1. Let _lRef_ be ? Evaluation of |RelationalExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |ShiftExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Let _r_ be ? IsLessThan(_lVal_, _rVal_, *true*).
+ 1. If _r_ is *undefined*, return *false*.
+ 1. Return _r_.
RelationalExpression : RelationalExpression `>` ShiftExpression
- 1. Let _lref_ be ? Evaluation of |RelationalExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |ShiftExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Let _r_ be ? IsLessThan(_rval_, _lval_, *false*).
- 1. If _r_ is *undefined*, return *false*. Otherwise, return _r_.
+ 1. Let _lRef_ be ? Evaluation of |RelationalExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |ShiftExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Let _r_ be ? IsLessThan(_rVal_, _lVal_, *false*).
+ 1. If _r_ is *undefined*, return *false*.
+ 1. Return _r_.
RelationalExpression : RelationalExpression `<=` ShiftExpression
- 1. Let _lref_ be ? Evaluation of |RelationalExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |ShiftExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Let _r_ be ? IsLessThan(_rval_, _lval_, *false*).
- 1. If _r_ is either *true* or *undefined*, return *false*. Otherwise, return *true*.
+ 1. Let _lRef_ be ? Evaluation of |RelationalExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |ShiftExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Let _r_ be ? IsLessThan(_rVal_, _lVal_, *false*).
+ 1. If _r_ is either *true* or *undefined*, return *false*.
+ 1. Return *true*.
RelationalExpression : RelationalExpression `>=` ShiftExpression
- 1. Let _lref_ be ? Evaluation of |RelationalExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |ShiftExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Let _r_ be ? IsLessThan(_lval_, _rval_, *true*).
- 1. If _r_ is either *true* or *undefined*, return *false*. Otherwise, return *true*.
+ 1. Let _lRef_ be ? Evaluation of |RelationalExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |ShiftExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Let _r_ be ? IsLessThan(_lVal_, _rVal_, *true*).
+ 1. If _r_ is either *true* or *undefined*, return *false*.
+ 1. Return *true*.
RelationalExpression : RelationalExpression `instanceof` ShiftExpression
- 1. Let _lref_ be ? Evaluation of |RelationalExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |ShiftExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Return ? InstanceofOperator(_lval_, _rval_).
+ 1. Let _lRef_ be ? Evaluation of |RelationalExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |ShiftExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Return ? InstanceofOperator(_lVal_, _rVal_).
RelationalExpression : RelationalExpression `in` ShiftExpression
- 1. Let _lref_ be ? Evaluation of |RelationalExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |ShiftExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. If _rval_ is not an Object, throw a *TypeError* exception.
- 1. Return ? HasProperty(_rval_, ? ToPropertyKey(_lval_)).
+ 1. Let _lRef_ be ? Evaluation of |RelationalExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |ShiftExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. If _rVal_ is not an Object, throw a *TypeError* exception.
+ 1. Return ? HasProperty(_rVal_, ? ToPropertyKey(_lVal_)).
RelationalExpression : PrivateIdentifier `in` ShiftExpression
1. Let _privateIdentifier_ be the StringValue of |PrivateIdentifier|.
- 1. Let _rref_ be ? Evaluation of |ShiftExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. If _rval_ is not an Object, throw a *TypeError* exception.
+ 1. Let _rRef_ be ? Evaluation of |ShiftExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. If _rVal_ is not an Object, throw a *TypeError* exception.
1. Let _privateEnv_ be the running execution context's PrivateEnvironment.
+ 1. Assert: _privateEnv_ is not *null*.
1. Let _privateName_ be ResolvePrivateIdentifier(_privateEnv_, _privateIdentifier_).
- 1. If PrivateElementFind(_rval_, _privateName_) is not ~empty~, return *true*.
- 1. Return *false*.
+ 1. If PrivateElementFind(_rVal_, _privateName_) is ~empty~, return *false*.
+ 1. Return *true*.
@@ -20177,18 +20505,18 @@
- description
- - It implements the generic algorithm for determining if _V_ is an instance of _target_ either by consulting _target_'s @@hasInstance method or, if absent, determining whether the value of _target_'s *"prototype"* property is present in _V_'s prototype chain.
+ - It implements the generic algorithm for determining if _V_ is an instance of _target_ either by consulting _target_'s %Symbol.hasInstance% method or, if absent, determining whether the value of _target_'s *"prototype"* property is present in _V_'s prototype chain.
1. If _target_ is not an Object, throw a *TypeError* exception.
- 1. Let _instOfHandler_ be ? GetMethod(_target_, @@hasInstance).
+ 1. Let _instOfHandler_ be ? GetMethod(_target_, %Symbol.hasInstance%).
1. If _instOfHandler_ is not *undefined*, then
1. Return ToBoolean(? Call(_instOfHandler_, _target_, « _V_ »)).
1. [id="step-instanceof-check-function"] If IsCallable(_target_) is *false*, throw a *TypeError* exception.
1. [id="step-instanceof-fallback"] Return ? OrdinaryHasInstance(_target_, _V_).
- Steps
+ Steps
@@ -20212,52 +20540,40 @@ Syntax
Runtime Semantics: Evaluation
EqualityExpression : EqualityExpression `==` RelationalExpression
- 1. Let _lref_ be ? Evaluation of |EqualityExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |RelationalExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Return ? IsLooselyEqual(_rval_, _lval_).
+ 1. Let _lRef_ be ? Evaluation of |EqualityExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |RelationalExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Return ? IsLooselyEqual(_rVal_, _lVal_).
EqualityExpression : EqualityExpression `!=` RelationalExpression
- 1. Let _lref_ be ? Evaluation of |EqualityExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |RelationalExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Let _r_ be ? IsLooselyEqual(_rval_, _lval_).
- 1. If _r_ is *true*, return *false*. Otherwise, return *true*.
+ 1. Let _lRef_ be ? Evaluation of |EqualityExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |RelationalExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Let _r_ be ? IsLooselyEqual(_rVal_, _lVal_).
+ 1. If _r_ is *true*, return *false*.
+ 1. Return *true*.
EqualityExpression : EqualityExpression `===` RelationalExpression
- 1. Let _lref_ be ? Evaluation of |EqualityExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |RelationalExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Return IsStrictlyEqual(_rval_, _lval_).
+ 1. Let _lRef_ be ? Evaluation of |EqualityExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |RelationalExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Return IsStrictlyEqual(_rVal_, _lVal_).
EqualityExpression : EqualityExpression `!==` RelationalExpression
- 1. Let _lref_ be ? Evaluation of |EqualityExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |RelationalExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Let _r_ be IsStrictlyEqual(_rval_, _lval_).
- 1. If _r_ is *true*, return *false*. Otherwise, return *true*.
+ 1. Let _lRef_ be ? Evaluation of |EqualityExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |RelationalExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Let _r_ be IsStrictlyEqual(_rVal_, _lVal_).
+ 1. If _r_ is *true*, return *false*.
+ 1. Return *true*.
-
- Given the above definition of equality:
-
- -
- String comparison can be forced by: `\`${a}\` == \`${b}\``.
-
- -
- Numeric comparison can be forced by: `+a == +b`.
-
- -
- Boolean comparison can be forced by: `!a == !b`.
-
-
-
The equality operators maintain the following invariants:
@@ -20351,31 +20667,27 @@ Syntax
Runtime Semantics: Evaluation
LogicalANDExpression : LogicalANDExpression `&&` BitwiseORExpression
- 1. Let _lref_ be ? Evaluation of |LogicalANDExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _lbool_ be ToBoolean(_lval_).
- 1. If _lbool_ is *false*, return _lval_.
- 1. Let _rref_ be ? Evaluation of |BitwiseORExpression|.
- 1. Return ? GetValue(_rref_).
+ 1. Let _lRef_ be ? Evaluation of |LogicalANDExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. If ToBoolean(_lVal_) is *false*, return _lVal_.
+ 1. Let _rRef_ be ? Evaluation of |BitwiseORExpression|.
+ 1. Return ? GetValue(_rRef_).
LogicalORExpression : LogicalORExpression `||` LogicalANDExpression
- 1. Let _lref_ be ? Evaluation of |LogicalORExpression|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _lbool_ be ToBoolean(_lval_).
- 1. If _lbool_ is *true*, return _lval_.
- 1. Let _rref_ be ? Evaluation of |LogicalANDExpression|.
- 1. Return ? GetValue(_rref_).
+ 1. Let _lRef_ be ? Evaluation of |LogicalORExpression|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. If ToBoolean(_lVal_) is *true*, return _lVal_.
+ 1. Let _rRef_ be ? Evaluation of |LogicalANDExpression|.
+ 1. Return ? GetValue(_rRef_).
CoalesceExpression : CoalesceExpressionHead `??` BitwiseORExpression
- 1. Let _lref_ be ? Evaluation of |CoalesceExpressionHead|.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. If _lval_ is either *undefined* or *null*, then
- 1. Let _rref_ be ? Evaluation of |BitwiseORExpression|.
- 1. Return ? GetValue(_rref_).
- 1. Else,
- 1. Return _lval_.
+ 1. Let _lRef_ be ? Evaluation of |CoalesceExpressionHead|.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. If _lVal_ is neither *undefined* nor *null*, return _lVal_.
+ 1. Let _rRef_ be ? Evaluation of |BitwiseORExpression|.
+ 1. Return ? GetValue(_rRef_).
@@ -20396,14 +20708,13 @@ Syntax
Runtime Semantics: Evaluation
ConditionalExpression : ShortCircuitExpression `?` AssignmentExpression `:` AssignmentExpression
- 1. Let _lref_ be ? Evaluation of |ShortCircuitExpression|.
- 1. Let _lval_ be ToBoolean(? GetValue(_lref_)).
- 1. If _lval_ is *true*, then
+ 1. Let _lRef_ be ? Evaluation of |ShortCircuitExpression|.
+ 1. Let _lVal_ be ToBoolean(? GetValue(_lRef_)).
+ 1. If _lVal_ is *true*, then
1. Let _trueRef_ be ? Evaluation of the first |AssignmentExpression|.
1. Return ? GetValue(_trueRef_).
- 1. Else,
- 1. Let _falseRef_ be ? Evaluation of the second |AssignmentExpression|.
- 1. Return ? GetValue(_falseRef_).
+ 1. Let _falseRef_ be ? Evaluation of the second |AssignmentExpression|.
+ 1. Return ? GetValue(_falseRef_).
@@ -20436,12 +20747,20 @@ Static Semantics: Early Errors
If |LeftHandSideExpression| is either an |ObjectLiteral| or an |ArrayLiteral|, |LeftHandSideExpression| must cover an |AssignmentPattern|.
-
- If |LeftHandSideExpression| is neither an |ObjectLiteral| nor an |ArrayLiteral|, it is a Syntax Error if the AssignmentTargetType of |LeftHandSideExpression| is not ~simple~.
+ If |LeftHandSideExpression| is neither an |ObjectLiteral| nor an |ArrayLiteral|, it is a Syntax Error if the AssignmentTargetType of |LeftHandSideExpression| is ~invalid~.
AssignmentExpression :
LeftHandSideExpression AssignmentOperator AssignmentExpression
+
+
+ -
+ It is a Syntax Error if the AssignmentTargetType of |LeftHandSideExpression| is ~invalid~.
+
+
+
+ AssignmentExpression :
LeftHandSideExpression `&&=` AssignmentExpression
LeftHandSideExpression `||=` AssignmentExpression
LeftHandSideExpression `??=` AssignmentExpression
@@ -20458,32 +20777,37 @@ Runtime Semantics: Evaluation
AssignmentExpression : LeftHandSideExpression `=` AssignmentExpression
1. If |LeftHandSideExpression| is neither an |ObjectLiteral| nor an |ArrayLiteral|, then
- 1. Let _lref_ be ? Evaluation of |LeftHandSideExpression|.
- 1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) and IsIdentifierRef of |LeftHandSideExpression| are both *true*, then
- 1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lref_.[[ReferencedName]].
+ 1. Let _lRef_ be ? Evaluation of |LeftHandSideExpression|.
+ 1. If the AssignmentTargetType of |LeftHandSideExpression| is ~web-compat~, throw a *ReferenceError* exception.
+ 1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true* and IsIdentifierRef of |LeftHandSideExpression| is *true*, then
+ 1. Let _lhs_ be the StringValue of |LeftHandSideExpression|.
+ 1. Let _rVal_ be ? NamedEvaluation of |AssignmentExpression| with argument _lhs_.
1. Else,
- 1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. [id="step-assignmentexpression-evaluation-simple-putvalue"] Perform ? PutValue(_lref_, _rval_).
- 1. Return _rval_.
+ 1. Let _rRef_ be ? Evaluation of |AssignmentExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. [id="step-assignmentexpression-evaluation-simple-putvalue"] Perform ? PutValue(_lRef_, _rVal_).
+ 1. Return _rVal_.
1. Let _assignmentPattern_ be the |AssignmentPattern| that is covered by |LeftHandSideExpression|.
- 1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Perform ? DestructuringAssignmentEvaluation of _assignmentPattern_ with argument _rval_.
- 1. Return _rval_.
+ 1. Let _rRef_ be ? Evaluation of |AssignmentExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Perform ? DestructuringAssignmentEvaluation of _assignmentPattern_ with argument _rVal_.
+ 1. Return _rVal_.
AssignmentExpression : LeftHandSideExpression AssignmentOperator AssignmentExpression
- 1. Let _lref_ be ? Evaluation of |LeftHandSideExpression|.
- 1. [id="step-assignmentexpression-evaluation-compound-getvalue"] Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
+ 1. Let _lRef_ be ? Evaluation of |LeftHandSideExpression|.
+ 1. If the AssignmentTargetType of |LeftHandSideExpression| is ~web-compat~, throw a *ReferenceError* exception.
+ 1. [id="step-assignmentexpression-evaluation-compound-getvalue"] Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |AssignmentExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
1. Let _assignmentOpText_ be the source text matched by |AssignmentOperator|.
1. Let _opText_ be the sequence of Unicode code points associated with _assignmentOpText_ in the following table:
- _assignmentOpText_ _opText_ _assignmentOpText_ _opText_ `**=` `**` `*=` `*` `/=` `/` Runtime Semantics: Evaluation
`|=` `|`
- 1. Let _r_ be ? ApplyStringOrNumericBinaryOperator(_lval_, _opText_, _rval_).
- 1. [id="step-assignmentexpression-evaluation-compound-putvalue"] Perform ? PutValue(_lref_, _r_).
+ 1. Let _r_ be ? ApplyStringOrNumericBinaryOperator(_lVal_, _opText_, _rVal_).
+ 1. [id="step-assignmentexpression-evaluation-compound-putvalue"] Perform ? PutValue(_lRef_, _r_).
1. Return _r_.
AssignmentExpression : LeftHandSideExpression `&&=` AssignmentExpression
- 1. Let _lref_ be ? Evaluation of |LeftHandSideExpression|.
- 1. [id="step-assignmentexpression-evaluation-lgcl-and-getvalue"] Let _lval_ be ? GetValue(_lref_).
- 1. Let _lbool_ be ToBoolean(_lval_).
- 1. If _lbool_ is *false*, return _lval_.
+ 1. Let _lRef_ be ? Evaluation of |LeftHandSideExpression|.
+ 1. [id="step-assignmentexpression-evaluation-lgcl-and-getvalue"] Let _lVal_ be ? GetValue(_lRef_).
+ 1. If ToBoolean(_lVal_) is *false*, return _lVal_.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true* and IsIdentifierRef of |LeftHandSideExpression| is *true*, then
- 1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lref_.[[ReferencedName]].
+ 1. Let _lhs_ be the StringValue of |LeftHandSideExpression|.
+ 1. Let _rVal_ be ? NamedEvaluation of |AssignmentExpression| with argument _lhs_.
1. Else,
- 1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. [id="step-assignmentexpression-evaluation-lgcl-and-putvalue"] Perform ? PutValue(_lref_, _rval_).
- 1. Return _rval_.
+ 1. Let _rRef_ be ? Evaluation of |AssignmentExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. [id="step-assignmentexpression-evaluation-lgcl-and-putvalue"] Perform ? PutValue(_lRef_, _rVal_).
+ 1. Return _rVal_.
AssignmentExpression : LeftHandSideExpression `||=` AssignmentExpression
- 1. Let _lref_ be ? Evaluation of |LeftHandSideExpression|.
- 1. [id="step-assignmentexpression-evaluation-lgcl-or-getvalue"] Let _lval_ be ? GetValue(_lref_).
- 1. Let _lbool_ be ToBoolean(_lval_).
- 1. If _lbool_ is *true*, return _lval_.
+ 1. Let _lRef_ be ? Evaluation of |LeftHandSideExpression|.
+ 1. [id="step-assignmentexpression-evaluation-lgcl-or-getvalue"] Let _lVal_ be ? GetValue(_lRef_).
+ 1. If ToBoolean(_lVal_) is *true*, return _lVal_.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true* and IsIdentifierRef of |LeftHandSideExpression| is *true*, then
- 1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lref_.[[ReferencedName]].
+ 1. Let _lhs_ be the StringValue of |LeftHandSideExpression|.
+ 1. Let _rVal_ be ? NamedEvaluation of |AssignmentExpression| with argument _lhs_.
1. Else,
- 1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. [id="step-assignmentexpression-evaluation-lgcl-or-putvalue"] Perform ? PutValue(_lref_, _rval_).
- 1. Return _rval_.
+ 1. Let _rRef_ be ? Evaluation of |AssignmentExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. [id="step-assignmentexpression-evaluation-lgcl-or-putvalue"] Perform ? PutValue(_lRef_, _rVal_).
+ 1. Return _rVal_.
AssignmentExpression : LeftHandSideExpression `??=` AssignmentExpression
- 1. Let _lref_ be ? Evaluation of |LeftHandSideExpression|.
- 1. [id="step-assignmentexpression-evaluation-lgcl-nullish-getvalue"] Let _lval_ be ? GetValue(_lref_).
- 1. If _lval_ is neither *undefined* nor *null*, return _lval_.
+ 1. Let _lRef_ be ? Evaluation of |LeftHandSideExpression|.
+ 1. [id="step-assignmentexpression-evaluation-lgcl-nullish-getvalue"] Let _lVal_ be ? GetValue(_lRef_).
+ 1. If _lVal_ is neither *undefined* nor *null*, return _lVal_.
1. If IsAnonymousFunctionDefinition(|AssignmentExpression|) is *true* and IsIdentifierRef of |LeftHandSideExpression| is *true*, then
- 1. Let _rval_ be ? NamedEvaluation of |AssignmentExpression| with argument _lref_.[[ReferencedName]].
+ 1. Let _lhs_ be the StringValue of |LeftHandSideExpression|.
+ 1. Let _rVal_ be ? NamedEvaluation of |AssignmentExpression| with argument _lhs_.
1. Else,
- 1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. [id="step-assignmentexpression-evaluation-lgcl-nullish-putvalue"] Perform ? PutValue(_lref_, _rval_).
- 1. Return _rval_.
+ 1. Let _rRef_ be ? Evaluation of |AssignmentExpression|.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. [id="step-assignmentexpression-evaluation-lgcl-nullish-putvalue"] Perform ? PutValue(_lRef_, _rVal_).
+ 1. Return _rVal_.
- When this expression occurs within strict mode code, it is a runtime error if _lref_ in step
+ When this expression occurs within strict mode code, it is a runtime error if _lRef_ in step
ApplyStringOrNumericBinaryOperator (
- _lval_: an ECMAScript language value,
+ _lVal_: an ECMAScript language value,
_opText_: `**`, `*`, `/`, `%`, `+`, `-`, `<<`, `>>`, `>>>`, `&`, `^`, or `|`,
- _rval_: an ECMAScript language value,
+ _rVal_: an ECMAScript language value,
): either a normal completion containing either a String, a BigInt, or a Number, or a throw completion
1. If _opText_ is `+`, then
- 1. [id="step-binary-op-toprimitive-lval"] Let _lprim_ be ? ToPrimitive(_lval_).
- 1. [id="step-binary-op-toprimitive-rval"] Let _rprim_ be ? ToPrimitive(_rval_).
- 1. [id="step-binary-op-string-check"] If _lprim_ is a String or _rprim_ is a String, then
- 1. Let _lstr_ be ? ToString(_lprim_).
- 1. Let _rstr_ be ? ToString(_rprim_).
- 1. Return the string-concatenation of _lstr_ and _rstr_.
- 1. Set _lval_ to _lprim_.
- 1. Set _rval_ to _rprim_.
+ 1. [id="step-binary-op-toprimitive-lval"] Let _lPrim_ be ? ToPrimitive(_lVal_).
+ 1. [id="step-binary-op-toprimitive-rval"] Let _rPrim_ be ? ToPrimitive(_rVal_).
+ 1. [id="step-binary-op-string-check"] If _lPrim_ is a String or _rPrim_ is a String, then
+ 1. Let _lStr_ be ? ToString(_lPrim_).
+ 1. Let _rStr_ be ? ToString(_rPrim_).
+ 1. Return the string-concatenation of _lStr_ and _rStr_.
+ 1. Set _lVal_ to _lPrim_.
+ 1. Set _rVal_ to _rPrim_.
1. NOTE: At this point, it must be a numeric operation.
- 1. Let _lnum_ be ? ToNumeric(_lval_).
- 1. Let _rnum_ be ? ToNumeric(_rval_).
- 1. If Type(_lnum_) is not Type(_rnum_), throw a *TypeError* exception.
- 1. If _lnum_ is a BigInt, then
- 1. If _opText_ is `**`, return ? BigInt::exponentiate(_lnum_, _rnum_).
- 1. If _opText_ is `/`, return ? BigInt::divide(_lnum_, _rnum_).
- 1. If _opText_ is `%`, return ? BigInt::remainder(_lnum_, _rnum_).
- 1. If _opText_ is `>>>`, return ? BigInt::unsignedRightShift(_lnum_, _rnum_).
- 1. Let _operation_ be the abstract operation associated with _opText_ and Type(_lnum_) in the following table:
-
-
-
- _opText_ Type(_lnum_) _operation_ `**` Number Number::exponentiate `*` Number Number::multiply `*` BigInt BigInt::multiply `/` Number Number::divide `%` Number Number::remainder `+` Number Number::add `+` BigInt BigInt::add `-` Number Number::subtract `-` BigInt BigInt::subtract `<<` Number Number::leftShift `<<` BigInt BigInt::leftShift `>>` Number Number::signedRightShift `>>` BigInt BigInt::signedRightShift `>>>` Number Number::unsignedRightShift `&` Number Number::bitwiseAND `&` BigInt BigInt::bitwiseAND `^` Number Number::bitwiseXOR `^` BigInt BigInt::bitwiseXOR `|` Number Number::bitwiseOR `|` BigInt BigInt::bitwiseOR
-
- 1. Return _operation_(_lnum_, _rnum_).
+ 1. Let _lNum_ be ? ToNumeric(_lVal_).
+ 1. Let _rNum_ be ? ToNumeric(_rVal_).
+ 1. If SameType(_lNum_, _rNum_) is *false*, throw a *TypeError* exception.
+ 1. If _lNum_ is a BigInt, then
+ 1. If _opText_ is `**`, return ? BigInt::exponentiate(_lNum_, _rNum_).
+ 1. If _opText_ is `/`, return ? BigInt::divide(_lNum_, _rNum_).
+ 1. If _opText_ is `%`, return ? BigInt::remainder(_lNum_, _rNum_).
+ 1. If _opText_ is `>>>`, return ? BigInt::unsignedRightShift(_lNum_, _rNum_).
+ 1. Let _operation_ be the abstract operation associated with _opText_ in the following table:
+
+
+
+
+ _opText_ _operation_ `*` BigInt::multiply `+` BigInt::add `-` BigInt::subtract `<<` BigInt::leftShift `>>` BigInt::signedRightShift `&` BigInt::bitwiseAND `^` BigInt::bitwiseXOR `|` BigInt::bitwiseOR
+
+ 1. Else,
+ 1. Assert: _lNum_ is a Number.
+ 1. Let _operation_ be the abstract operation associated with _opText_ in the following table:
+
+
+
+
+ _opText_ _operation_ `**` Number::exponentiate `*` Number::multiply `/` Number::divide `%` Number::remainder `+` Number::add `-` Number::subtract `<<` Number::leftShift `>>` Number::signedRightShift `>>>` Number::unsignedRightShift `&` Number::bitwiseAND `^` Number::bitwiseXOR `|` Number::bitwiseOR
+
+ 1. Return _operation_(_lNum_, _rNum_).
No hint is provided in the calls to ToPrimitive in steps
@@ -20625,11 +20967,11 @@
- 1. Let _lref_ be ? Evaluation of _leftOperand_.
- 1. Let _lval_ be ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of _rightOperand_.
- 1. Let _rval_ be ? GetValue(_rref_).
- 1. Return ? ApplyStringOrNumericBinaryOperator(_lval_, _opText_, _rval_).
+ 1. Let _lRef_ be ? Evaluation of _leftOperand_.
+ 1. Let _lVal_ be ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of _rightOperand_.
+ 1. Let _rVal_ be ? GetValue(_rRef_).
+ 1. Return ? ApplyStringOrNumericBinaryOperator(_lVal_, _opText_, _rVal_).
@@ -20815,7 +21157,7 @@
AssignmentProperty : IdentifierReference Initializer?
1. Let _P_ be the StringValue of |IdentifierReference|.
- 1. Let _lref_ be ? ResolveBinding(_P_).
+ 1. Let _lRef_ be ? ResolveBinding(_P_).
1. Let _v_ be ? GetV(_value_, _P_).
1. If |Initializer| is present and _v_ is *undefined*, then
1. If IsAnonymousFunctionDefinition(|Initializer|) is *true*, then
@@ -20823,7 +21165,7 @@
1. Else,
1. Let _defaultValue_ be ? Evaluation of |Initializer|.
1. Set _v_ to ? GetValue(_defaultValue_).
- 1. Perform ? PutValue(_lref_, _v_).
+ 1. Perform ? PutValue(_lRef_, _v_).
1. Return « _P_ ».
@@ -20846,10 +21188,10 @@
AssignmentRestProperty : `...` DestructuringAssignmentTarget
- 1. Let _lref_ be ? Evaluation of |DestructuringAssignmentTarget|.
+ 1. Let _lRef_ be ? Evaluation of |DestructuringAssignmentTarget|.
1. Let _restObj_ be OrdinaryObjectCreate(%Object.prototype%).
1. Perform ? CopyDataProperties(_restObj_, _value_, _excludedNames_).
- 1. Return ? PutValue(_lref_, _restObj_).
+ 1. Return ? PutValue(_lRef_, _restObj_).
@@ -20895,7 +21237,7 @@
AssignmentElement : DestructuringAssignmentTarget Initializer?
1. If |DestructuringAssignmentTarget| is neither an |ObjectLiteral| nor an |ArrayLiteral|, then
- 1. Let _lref_ be ? Evaluation of |DestructuringAssignmentTarget|.
+ 1. Let _lRef_ be ? Evaluation of |DestructuringAssignmentTarget|.
1. Let _value_ be *undefined*.
1. If _iteratorRecord_.[[Done]] is *false*, then
1. Let _next_ be ? IteratorStepValue(_iteratorRecord_).
@@ -20903,7 +21245,8 @@
1. Set _value_ to _next_.
1. If |Initializer| is present and _value_ is *undefined*, then
1. If IsAnonymousFunctionDefinition(|Initializer|) is *true* and IsIdentifierRef of |DestructuringAssignmentTarget| is *true*, then
- 1. Let _v_ be ? NamedEvaluation of |Initializer| with argument _lref_.[[ReferencedName]].
+ 1. Let _target_ be the StringValue of |DestructuringAssignmentTarget|.
+ 1. Let _v_ be ? NamedEvaluation of |Initializer| with argument _target_.
1. Else,
1. Let _defaultValue_ be ? Evaluation of |Initializer|.
1. Let _v_ be ? GetValue(_defaultValue_).
@@ -20912,7 +21255,7 @@
1. If |DestructuringAssignmentTarget| is either an |ObjectLiteral| or an |ArrayLiteral|, then
1. Let _nestedAssignmentPattern_ be the |AssignmentPattern| that is covered by |DestructuringAssignmentTarget|.
1. Return ? DestructuringAssignmentEvaluation of _nestedAssignmentPattern_ with argument _v_.
- 1. Return ? PutValue(_lref_, _v_).
+ 1. Return ? PutValue(_lRef_, _v_).
Left to right evaluation order is maintained by evaluating a |DestructuringAssignmentTarget| that is not a destructuring pattern prior to accessing the iterator or evaluating the |Initializer|.
@@ -20920,7 +21263,7 @@
AssignmentRestElement : `...` DestructuringAssignmentTarget
1. If |DestructuringAssignmentTarget| is neither an |ObjectLiteral| nor an |ArrayLiteral|, then
- 1. Let _lref_ be ? Evaluation of |DestructuringAssignmentTarget|.
+ 1. Let _lRef_ be ? Evaluation of |DestructuringAssignmentTarget|.
1. Let _A_ be ! ArrayCreate(0).
1. Let _n_ be 0.
1. Repeat, while _iteratorRecord_.[[Done]] is *false*,
@@ -20929,7 +21272,7 @@
1. Perform ! CreateDataPropertyOrThrow(_A_, ! ToString(𝔽(_n_)), _next_).
1. Set _n_ to _n_ + 1.
1. If |DestructuringAssignmentTarget| is neither an |ObjectLiteral| nor an |ArrayLiteral|, then
- 1. Return ? PutValue(_lref_, _A_).
+ 1. Return ? PutValue(_lRef_, _A_).
1. Let _nestedAssignmentPattern_ be the |AssignmentPattern| that is covered by |DestructuringAssignmentTarget|.
1. Return ? DestructuringAssignmentEvaluation of _nestedAssignmentPattern_ with argument _A_.
@@ -20947,11 +21290,12 @@
AssignmentElement : DestructuringAssignmentTarget Initializer?
1. If |DestructuringAssignmentTarget| is neither an |ObjectLiteral| nor an |ArrayLiteral|, then
- 1. Let _lref_ be ? Evaluation of |DestructuringAssignmentTarget|.
+ 1. Let _lRef_ be ? Evaluation of |DestructuringAssignmentTarget|.
1. Let _v_ be ? GetV(_value_, _propertyName_).
1. If |Initializer| is present and _v_ is *undefined*, then
- 1. If IsAnonymousFunctionDefinition(|Initializer|) and IsIdentifierRef of |DestructuringAssignmentTarget| are both *true*, then
- 1. Let _rhsValue_ be ? NamedEvaluation of |Initializer| with argument _lref_.[[ReferencedName]].
+ 1. If IsAnonymousFunctionDefinition(|Initializer|) is *true* and IsIdentifierRef of |DestructuringAssignmentTarget| is *true*, then
+ 1. Let _target_ be the StringValue of |DestructuringAssignmentTarget|.
+ 1. Let _rhsValue_ be ? NamedEvaluation of |Initializer| with argument _target_.
1. Else,
1. Let _defaultValue_ be ? Evaluation of |Initializer|.
1. Let _rhsValue_ be ? GetValue(_defaultValue_).
@@ -20960,7 +21304,7 @@
1. If |DestructuringAssignmentTarget| is either an |ObjectLiteral| or an |ArrayLiteral|, then
1. Let _assignmentPattern_ be the |AssignmentPattern| that is covered by |DestructuringAssignmentTarget|.
1. Return ? DestructuringAssignmentEvaluation of _assignmentPattern_ with argument _rhsValue_.
- 1. Return ? PutValue(_lref_, _rhsValue_).
+ 1. Return ? PutValue(_lRef_, _rhsValue_).
@@ -20979,10 +21323,10 @@ Syntax
Runtime Semantics: Evaluation
Expression : Expression `,` AssignmentExpression
- 1. Let _lref_ be ? Evaluation of |Expression|.
- 1. Perform ? GetValue(_lref_).
- 1. Let _rref_ be ? Evaluation of |AssignmentExpression|.
- 1. Return ? GetValue(_rref_).
+ 1. Let _lRef_ be ? Evaluation of |Expression|.
+ 1. Perform ? GetValue(_lRef_).
+ 1. Let _rRef_ be ? Evaluation of |AssignmentExpression|.
+ 1. Return ? GetValue(_rRef_).
GetValue must be called even though its value is not used because it may have observable side-effects.
@@ -21078,12 +21422,16 @@ Syntax
Declaration[?Yield, ?Await]
-
+
Static Semantics: Early Errors
Block : `{` StatementList `}`
-
- It is a Syntax Error if the LexicallyDeclaredNames of |StatementList| contains any duplicate entries.
+
It is a Syntax Error if the LexicallyDeclaredNames of |StatementList| contains any duplicate entries, unless the host is a web browser or otherwise supports
+
+ - IsStrict(this production) is *false*.
+ - The duplicate entries are only bound by FunctionDeclarations.
+
-
It is a Syntax Error if any element of the LexicallyDeclaredNames of |StatementList| also occurs in the VarDeclaredNames of |StatementList|.
@@ -21126,7 +21474,7 @@
Runtime Semantics: Evaluation
-
+
BlockDeclarationInstantiation (
_code_: a Parse Node,
@@ -21141,11 +21489,6 @@
When a |Block| or |CaseBlock| is evaluated a new Declarative Environment Record is created and bindings for each block scoped variable, constant, function, or class declared in the block are instantiated in the Environment Record.
It performs the following steps when called:
-
1. Let _declarations_ be the LexicallyScopedDeclarations of _code_.
1. Let _privateEnv_ be the running execution context's PrivateEnvironment.
@@ -21154,11 +21497,22 @@
1. If IsConstantDeclaration of _d_ is *true*, then
1. Perform ! _env_.CreateImmutableBinding(_dn_, *true*).
1. Else,
- 1. [id="step-blockdeclarationinstantiation-createmutablebinding"] Perform ! _env_.CreateMutableBinding(_dn_, *false*). NOTE: This step is replaced in section
@@ -21305,8 +21659,8 @@ Runtime Semantics: Evaluation
VariableDeclaration : BindingPattern Initializer
1. Let _rhs_ be ? Evaluation of |Initializer|.
- 1. Let _rval_ be ? GetValue(_rhs_).
- 1. Return ? BindingInitialization of |BindingPattern| with arguments _rval_ and *undefined*.
+ 1. Let _rVal_ be ? GetValue(_rhs_).
+ 1. Return ? BindingInitialization of |BindingPattern| with arguments _rVal_ and *undefined*.
@@ -21538,11 +21892,9 @@ Runtime Semantics: Evaluation
1. Let _exprRef_ be ? Evaluation of |Expression|.
1. Let _exprValue_ be ToBoolean(? GetValue(_exprRef_)).
- 1. If _exprValue_ is *false*, then
- 1. Return *undefined*.
- 1. Else,
- 1. Let _stmtCompletion_ be Completion(Evaluation of |Statement|).
- 1. Return ? UpdateEmpty(_stmtCompletion_, *undefined*).
+ 1. If _exprValue_ is *false*, return *undefined*.
+ 1. Let _stmtCompletion_ be Completion(Evaluation of |Statement|).
+ 1. Return ? UpdateEmpty(_stmtCompletion_, *undefined*).
@@ -21742,15 +22094,15 @@
1. If the first |Expression| is present, then
1. Let _exprRef_ be ? Evaluation of the first |Expression|.
1. Perform ? GetValue(_exprRef_).
- 1. If the second |Expression| is present, let _test_ be the second |Expression|; otherwise, let _test_ be ~empty~.
- 1. If the third |Expression| is present, let _increment_ be the third |Expression|; otherwise, let _increment_ be ~empty~.
+ 1. If the second |Expression| is present, let _test_ be the second |Expression|; else let _test_ be ~empty~.
+ 1. If the third |Expression| is present, let _increment_ be the third |Expression|; else let _increment_ be ~empty~.
1. Return ? ForBodyEvaluation(_test_, _increment_, |Statement|, « », _labelSet_).
ForStatement : `for` `(` `var` VariableDeclarationList `;` Expression? `;` Expression? `)` Statement
1. Perform ? Evaluation of |VariableDeclarationList|.
- 1. If the first |Expression| is present, let _test_ be the first |Expression|; otherwise, let _test_ be ~empty~.
- 1. If the second |Expression| is present, let _increment_ be the second |Expression|; otherwise, let _increment_ be ~empty~.
+ 1. If the first |Expression| is present, let _test_ be the first |Expression|; else let _test_ be ~empty~.
+ 1. If the second |Expression| is present, let _increment_ be the second |Expression|; else let _increment_ be ~empty~.
1. Return ? ForBodyEvaluation(_test_, _increment_, |Statement|, « », _labelSet_).
ForStatement : `for` `(` LexicalDeclaration Expression? `;` Expression? `)` Statement
@@ -21769,9 +22121,9 @@
1. If _forDcl_ is an abrupt completion, then
1. Set the running execution context's LexicalEnvironment to _oldEnv_.
1. Return ? _forDcl_.
- 1. If _isConst_ is *false*, let _perIterationLets_ be _boundNames_; otherwise let _perIterationLets_ be a new empty List.
- 1. If the first |Expression| is present, let _test_ be the first |Expression|; otherwise, let _test_ be ~empty~.
- 1. If the second |Expression| is present, let _increment_ be the second |Expression|; otherwise, let _increment_ be ~empty~.
+ 1. If _isConst_ is *false*, let _perIterationLets_ be _boundNames_; else let _perIterationLets_ be a new empty List.
+ 1. If the first |Expression| is present, let _test_ be the first |Expression|; else let _test_ be ~empty~.
+ 1. If the second |Expression| is present, let _increment_ be the second |Expression|; else let _increment_ be ~empty~.
1. Let _bodyResult_ be Completion(ForBodyEvaluation(_test_, _increment_, |Statement|, _perIterationLets_, _labelSet_)).
1. Set the running execution context's LexicalEnvironment to _oldEnv_.
1. Return ? _bodyResult_.
@@ -21891,7 +22243,7 @@ Static Semantics: Early Errors
If |LeftHandSideExpression| is either an |ObjectLiteral| or an |ArrayLiteral|, |LeftHandSideExpression| must cover an |AssignmentPattern|.
-
- If |LeftHandSideExpression| is neither an |ObjectLiteral| nor an |ArrayLiteral|, it is a Syntax Error if the AssignmentTargetType of |LeftHandSideExpression| is not ~simple~.
+ If |LeftHandSideExpression| is neither an |ObjectLiteral| nor an |ArrayLiteral|, it is a Syntax Error if the AssignmentTargetType of |LeftHandSideExpression| is ~invalid~.
@@ -22088,11 +22440,10 @@
1. Let _iterator_ be EnumerateObjectProperties(_obj_).
1. Let _nextMethod_ be ! GetV(_iterator_, *"next"*).
1. Return the Iterator Record { [[Iterator]]: _iterator_, [[NextMethod]]: _nextMethod_, [[Done]]: *false* }.
- 1. Else,
- 1. Assert: _iterationKind_ is either ~iterate~ or ~async-iterate~.
- 1. If _iterationKind_ is ~async-iterate~, let _iteratorKind_ be ~async~.
- 1. Else, let _iteratorKind_ be ~sync~.
- 1. Return ? GetIterator(_exprValue_, _iteratorKind_).
+ 1. Assert: _iterationKind_ is either ~iterate~ or ~async-iterate~.
+ 1. If _iterationKind_ is ~async-iterate~, let _iteratorKind_ be ~async~.
+ 1. Else, let _iteratorKind_ be ~sync~.
+ 1. Return ? GetIterator(_exprValue_, _iteratorKind_).
@@ -22135,6 +22486,7 @@
1. Let _status_ be Completion(BindingInitialization of _lhs_ with arguments _nextValue_ and *undefined*).
1. Else,
1. Let _lhsRef_ be Completion(Evaluation of _lhs_). (It may be evaluated repeatedly.)
+ 1. If _lhsKind_ is ~assignment~ and the AssignmentTargetType of _lhs_ is ~web-compat~, throw a *ReferenceError* exception.
1. If _lhsRef_ is an abrupt completion, then
1. Let _status_ be _lhsRef_.
1. Else,
@@ -22154,22 +22506,18 @@
1. Let _status_ be Completion(InitializeReferencedBinding(_lhsRef_, _nextValue_)).
1. If _status_ is an abrupt completion, then
1. Set the running execution context's LexicalEnvironment to _oldEnv_.
+ 1. If _iterationKind_ is ~enumerate~, return ? _status_.
+ 1. Assert: _iterationKind_ is ~iterate~.
1. If _iteratorKind_ is ~async~, return ? AsyncIteratorClose(_iteratorRecord_, _status_).
- 1. If _iterationKind_ is ~enumerate~, then
- 1. Return ? _status_.
- 1. Else,
- 1. Assert: _iterationKind_ is ~iterate~.
- 1. Return ? IteratorClose(_iteratorRecord_, _status_).
+ 1. Return ? IteratorClose(_iteratorRecord_, _status_).
1. Let _result_ be Completion(Evaluation of _stmt_).
1. Set the running execution context's LexicalEnvironment to _oldEnv_.
1. If LoopContinues(_result_, _labelSet_) is *false*, then
- 1. If _iterationKind_ is ~enumerate~, then
- 1. Return ? UpdateEmpty(_result_, _V_).
- 1. Else,
- 1. Assert: _iterationKind_ is ~iterate~.
- 1. Set _status_ to Completion(UpdateEmpty(_result_, _V_)).
- 1. If _iteratorKind_ is ~async~, return ? AsyncIteratorClose(_iteratorRecord_, _status_).
- 1. Return ? IteratorClose(_iteratorRecord_, _status_).
+ 1. Set _status_ to Completion(UpdateEmpty(_result_, _V_)).
+ 1. If _iterationKind_ is ~enumerate~, return ? _status_.
+ 1. Assert: _iterationKind_ is ~iterate~.
+ 1. If _iteratorKind_ is ~async~, return ? AsyncIteratorClose(_iteratorRecord_, _status_).
+ 1. Return ? IteratorClose(_iteratorRecord_, _status_).
1. If _result_.[[Value]] is not ~empty~, set _V_ to _result_.[[Value]].
@@ -22192,12 +22540,12 @@ Runtime Semantics: Evaluation
EnumerateObjectProperties (
_O_: an Object,
- ): an Iterator
+ ): an iterator object
- 1. Return an Iterator object (
The iterator's `throw` and `return` methods are *null* and are never invoked. The iterator's `next` method processes object properties to determine whether the property key should be returned as an iterator value. Returned property keys do not include keys that are Symbols. Properties of the target object may be deleted during enumeration. A property that is deleted before it is processed by the iterator's `next` method is ignored. If new properties are added to the target object during enumeration, the newly added properties are not guaranteed to be processed in the active enumeration. A property name will be returned by the iterator's `next` method at most once in any enumeration.
Enumerating the properties of the target object includes enumerating properties of its prototype, and the prototype of the prototype, and so on, recursively; but a property of a prototype is not processed if it has the same name as a property that has already been processed by the iterator's `next` method. The values of [[Enumerable]] attributes are not considered when determining if a property of a prototype object has already been processed. The enumerable property names of prototype objects must be obtained by invoking EnumerateObjectProperties passing the prototype object as the argument. EnumerateObjectProperties must obtain the own property keys of the target object by calling its [[OwnPropertyKeys]] internal method. Property attributes of the target object must be obtained by calling its [[GetOwnProperty]] internal method.
@@ -22238,7 +22586,7 @@
For-In Iterator Objects
- A For-In Iterator is an object that represents a specific iteration over some specific object. For-In Iterator objects are never directly accessible to ECMAScript code; they exist solely to illustrate the behaviour of EnumerateObjectProperties.
+ A For-In Iterator is an object that represents a specific iteration over some specific object. For-In Iterator objects are never directly accessible to ECMAScript code; they exist solely to illustrate the behaviour of EnumerateObjectProperties.
@@ -22264,19 +22612,19 @@
The %ForInIteratorPrototype% Object
The %ForInIteratorPrototype% object:
- - has properties that are inherited by all For-In Iterator Objects.
+ - has properties that are inherited by all For-In Iterator objects.
- is an ordinary object.
- - has a [[Prototype]] internal slot whose value is %IteratorPrototype%.
+ - has a [[Prototype]] internal slot whose value is %Iterator.prototype%.
- is never directly accessible to ECMAScript code.
- has the following properties:
-
+
%ForInIteratorPrototype%.next ( )
1. Let _O_ be the *this* value.
1. Assert: _O_ is an Object.
- 1. Assert: _O_ has all of the internal slots of a For-In Iterator Instance (%ForInIteratorPrototype%.next ( )
1. Let _r_ be the first element of _O_.[[RemainingKeys]].
1. Remove the first element from _O_.[[RemainingKeys]].
1. If _O_.[[VisitedKeys]] does not contain _r_, then
- 1. Let _desc_ be ? _object_.[[GetOwnProperty]] (_r_).
+ 1. Let _desc_ be ? _object_.[[GetOwnProperty]](_r_) .
1. If _desc_ is not *undefined*, then
1. Append _r_ to _O_.[[VisitedKeys]].
- 1. If _desc_.[[Enumerable]] is *true*, return CreateIterResultObject(_r_, *false*).
+ 1. If _desc_.[[Enumerable]] is *true*, return CreateIteratorResultObject(_r_, *false*).
1. Set _object_ to ? _object_.[[GetPrototypeOf]]() .
1. Set _O_.[[Object]] to _object_.
1. Set _O_.[[ObjectWasVisited]] to *false*.
- 1. If _object_ is *null*, return CreateIterResultObject(*undefined*, *true*).
+ 1. If _object_ is *null*, return CreateIteratorResultObject(*undefined*, *true*).
@@ -22306,17 +22654,19 @@ Properties of For-In Iterator Instances
For-In Iterator instances are ordinary objects that inherit properties from the %ForInIteratorPrototype% intrinsic object. For-In Iterator instances are initially created with the internal slots listed in
-
-
- Internal Slot
-
-
- Type
-
-
- Description
-
-
+
+
+
+ Internal Slot
+
+
+ Type
+
+
+ Description
+
+
+
[[Object]]
@@ -22454,14 +22804,14 @@ Syntax
Runtime Semantics: Evaluation
ReturnStatement : `return` `;`
- 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: *undefined*, [[Target]]: ~empty~ }.
+ 1. Return ReturnCompletion(*undefined*).
ReturnStatement : `return` Expression `;`
1. Let _exprRef_ be ? Evaluation of |Expression|.
1. Let _exprValue_ be ? GetValue(_exprRef_).
1. If GetGeneratorKind() is ~async~, set _exprValue_ to ? Await(_exprValue_).
- 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _exprValue_, [[Target]]: ~empty~ }.
+ 1. Return ReturnCompletion(_exprValue_).
@@ -22538,12 +22888,16 @@ Syntax
`default` `:` StatementList[?Yield, ?Await, ?Return]?
-
+
Static Semantics: Early Errors
SwitchStatement : `switch` `(` Expression `)` CaseBlock
-
- It is a Syntax Error if the LexicallyDeclaredNames of |CaseBlock| contains any duplicate entries.
+
It is a Syntax Error if the LexicallyDeclaredNames of |CaseBlock| contains any duplicate entries, unless the host is a web browser or otherwise supports
+
+ - IsStrict(this production) is *false*.
+ - The duplicate entries are only bound by FunctionDeclarations.
+
-
It is a Syntax Error if any element of the LexicallyDeclaredNames of |CaseBlock| also occurs in the VarDeclaredNames of |CaseBlock|.
@@ -22696,12 +23050,9 @@
Static Semantics: Early Errors
LabelledItem : FunctionDeclaration
-
- It is a Syntax Error if any source text is matched by this production.
+ It is a Syntax Error if any source text is matched by this production, unless that source text is non-strict code and the host is a web browser or otherwise supports
-
- An alternative definition for this rule is provided in
-
@@ -22733,7 +23084,7 @@ Runtime Semantics: Evaluation
Runtime Semantics: LabelledEvaluation (
_labelSet_: a List of Strings,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ ): either a normal completion containing either an ECMAScript language value or ~empty~, or an abrupt completion
@@ -22849,19 +23200,16 @@ Static Semantics: Early Errors
It is a Syntax Error if any element of the BoundNames of |CatchParameter| also occurs in the LexicallyDeclaredNames of |Block|.
-
- It is a Syntax Error if any element of the BoundNames of |CatchParameter| also occurs in the VarDeclaredNames of |Block|.
+ It is a Syntax Error if any element of the BoundNames of |CatchParameter| also occurs in the VarDeclaredNames of |Block|, unless |CatchParameter| is
CatchParameter : BindingIdentifier and the host is a web browser or otherwise supports
-
- An alternative static semantics for this production is given in
-
Runtime Semantics: CatchClauseEvaluation (
_thrownValue_: an ECMAScript language value,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ ): either a normal completion containing either an ECMAScript language value or ~empty~, or an abrupt completion
@@ -22935,8 +23283,7 @@ Runtime Semantics: Evaluation
1. If an implementation-defined debugging facility is available and enabled, then
1. Perform an implementation-defined debugging action.
1. Return a new implementation-defined Completion Record.
- 1. Else,
- 1. Return ~empty~.
+ 1. Return ~empty~.
@@ -23192,7 +23539,7 @@ Static Semantics: HasInitializer ( ): a Boolean
- Static Semantics: ExpectedArgumentCount ( ): an integer
+ Static Semantics: ExpectedArgumentCount ( ): a non-negative integer
@@ -23327,7 +23674,8 @@ Static Semantics: FunctionBodyContainsUseStrict ( ): a Boolean
FunctionBody : FunctionStatementList
- 1. If the Directive Prologue of |FunctionBody| contains a Use Strict Directive, return *true*; otherwise, return *false*.
+ 1. If the Directive Prologue of |FunctionBody| contains a Use Strict Directive, return *true*.
+ 1. Return *false*.
@@ -23336,14 +23684,16 @@
Runtime Semantics: EvaluateFunctionBody (
_functionObject_: an ECMAScript function object,
_argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ ): a return completion or a throw completion
FunctionBody : FunctionStatementList
1. Perform ? FunctionDeclarationInstantiation(_functionObject_, _argumentsList_).
- 1. Return ? Evaluation of |FunctionStatementList|.
+ 1. Perform ? Evaluation of |FunctionStatementList|.
+ 1. NOTE: If the previous step resulted in a normal completion, then evaluation finished by proceeding past the end of the |FunctionStatementList|.
+ 1. Return ReturnCompletion(*undefined*).
@@ -23424,7 +23774,7 @@ Runtime Semantics: Evaluation
1. Return ~empty~.
- An alternative semantics is provided in
+ An alternative semantics is provided by
FunctionDeclaration : `function` `(` FormalParameters `)` `{` FunctionBody `}`
@@ -23519,7 +23869,7 @@
Runtime Semantics: EvaluateConciseBody (
_functionObject_: an ECMAScript function object,
_argumentsList_: a List of ECMAScript language values,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ ): a return completion or a throw completion
@@ -23563,7 +23913,7 @@ Runtime Semantics: Evaluation
1. Let _exprRef_ be ? Evaluation of |AssignmentExpression|.
1. Let _exprValue_ be ? GetValue(_exprRef_).
- 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _exprValue_, [[Target]]: ~empty~ }.
+ 1. Return ReturnCompletion(_exprValue_).
@@ -23719,10 +24069,9 @@
1. Perform SetFunctionName(_closure_, _propKey_, *"get"*).
1. If _propKey_ is a Private Name, then
1. Return PrivateElement { [[Key]]: _propKey_, [[Kind]]: ~accessor~, [[Get]]: _closure_, [[Set]]: *undefined* }.
- 1. Else,
- 1. Let _desc_ be the PropertyDescriptor { [[Get]]: _closure_, [[Enumerable]]: _enumerable_, [[Configurable]]: *true* }.
- 1. Perform ? DefinePropertyOrThrow(_object_, _propKey_, _desc_).
- 1. Return ~unused~.
+ 1. Let _desc_ be the PropertyDescriptor { [[Get]]: _closure_, [[Enumerable]]: _enumerable_, [[Configurable]]: *true* }.
+ 1. Perform ? DefinePropertyOrThrow(_object_, _propKey_, _desc_).
+ 1. Return ~unused~.
MethodDefinition : `set` ClassElementName `(` PropertySetParameterList `)` `{` FunctionBody `}`
@@ -23735,10 +24084,9 @@
1. Perform SetFunctionName(_closure_, _propKey_, *"set"*).
1. If _propKey_ is a Private Name, then
1. Return PrivateElement { [[Key]]: _propKey_, [[Kind]]: ~accessor~, [[Get]]: *undefined*, [[Set]]: _closure_ }.
- 1. Else,
- 1. Let _desc_ be the PropertyDescriptor { [[Set]]: _closure_, [[Enumerable]]: _enumerable_, [[Configurable]]: *true* }.
- 1. Perform ? DefinePropertyOrThrow(_object_, _propKey_, _desc_).
- 1. Return ~unused~.
+ 1. Let _desc_ be the PropertyDescriptor { [[Set]]: _closure_, [[Enumerable]]: _enumerable_, [[Configurable]]: *true* }.
+ 1. Perform ? DefinePropertyOrThrow(_object_, _propKey_, _desc_).
+ 1. Return ~unused~.
GeneratorMethod : `*` ClassElementName `(` UniqueFormalParameters `)` `{` GeneratorBody `}`
@@ -23749,7 +24097,7 @@
1. Let _closure_ be OrdinaryFunctionCreate(%GeneratorFunction.prototype%, _sourceText_, |UniqueFormalParameters|, |GeneratorBody|, ~non-lexical-this~, _env_, _privateEnv_).
1. Perform MakeMethod(_closure_, _object_).
1. Perform SetFunctionName(_closure_, _propKey_).
- 1. Let _prototype_ be OrdinaryObjectCreate(%GeneratorFunction.prototype.prototype%).
+ 1. Let _prototype_ be OrdinaryObjectCreate(%GeneratorPrototype%).
1. Perform ! DefinePropertyOrThrow(_closure_, *"prototype"*, PropertyDescriptor { [[Value]]: _prototype_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return ? DefineMethodProperty(_object_, _propKey_, _closure_, _enumerable_).
@@ -23764,7 +24112,7 @@
1. Let _closure_ be OrdinaryFunctionCreate(%AsyncGeneratorFunction.prototype%, _sourceText_, |UniqueFormalParameters|, |AsyncGeneratorBody|, ~non-lexical-this~, _env_, _privateEnv_).
1. Perform MakeMethod(_closure_, _object_).
1. Perform SetFunctionName(_closure_, _propKey_).
- 1. Let _prototype_ be OrdinaryObjectCreate(%AsyncGeneratorFunction.prototype.prototype%).
+ 1. Let _prototype_ be OrdinaryObjectCreate(%AsyncGeneratorPrototype%).
1. Perform ! DefinePropertyOrThrow(_closure_, *"prototype"*, PropertyDescriptor { [[Value]]: _prototype_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return ? DefineMethodProperty(_object_, _propKey_, _closure_, _enumerable_).
@@ -23884,10 +24232,11 @@
GeneratorBody : FunctionBody
1. Perform ? FunctionDeclarationInstantiation(_functionObject_, _argumentsList_).
- 1. Let _G_ be ? OrdinaryCreateFromConstructor(_functionObject_, *"%GeneratorFunction.prototype.prototype%"*, « [[GeneratorState]], [[GeneratorContext]], [[GeneratorBrand]] »).
+ 1. Let _G_ be ? OrdinaryCreateFromConstructor(_functionObject_, *"%GeneratorPrototype%"*, « [[GeneratorState]], [[GeneratorContext]], [[GeneratorBrand]] »).
1. Set _G_.[[GeneratorBrand]] to ~empty~.
+ 1. Set _G_.[[GeneratorState]] to ~suspended-start~.
1. Perform GeneratorStart(_G_, |FunctionBody|).
- 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _G_, [[Target]]: ~empty~ }.
+ 1. Return ReturnCompletion(_G_).
@@ -23906,7 +24255,7 @@
1. Let _sourceText_ be the source text matched by |GeneratorDeclaration|.
1. Let _F_ be OrdinaryFunctionCreate(%GeneratorFunction.prototype%, _sourceText_, |FormalParameters|, |GeneratorBody|, ~non-lexical-this~, _env_, _privateEnv_).
1. Perform SetFunctionName(_F_, _name_).
- 1. Let _prototype_ be OrdinaryObjectCreate(%GeneratorFunction.prototype.prototype%).
+ 1. Let _prototype_ be OrdinaryObjectCreate(%GeneratorPrototype%).
1. Perform ! DefinePropertyOrThrow(_F_, *"prototype"*, PropertyDescriptor { [[Value]]: _prototype_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return _F_.
@@ -23915,7 +24264,7 @@
1. Let _sourceText_ be the source text matched by |GeneratorDeclaration|.
1. Let _F_ be OrdinaryFunctionCreate(%GeneratorFunction.prototype%, _sourceText_, |FormalParameters|, |GeneratorBody|, ~non-lexical-this~, _env_, _privateEnv_).
1. Perform SetFunctionName(_F_, *"default"*).
- 1. Let _prototype_ be OrdinaryObjectCreate(%GeneratorFunction.prototype.prototype%).
+ 1. Let _prototype_ be OrdinaryObjectCreate(%GeneratorPrototype%).
1. Perform ! DefinePropertyOrThrow(_F_, *"prototype"*, PropertyDescriptor { [[Value]]: _prototype_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return _F_.
@@ -23940,7 +24289,7 @@
1. Let _sourceText_ be the source text matched by |GeneratorExpression|.
1. Let _closure_ be OrdinaryFunctionCreate(%GeneratorFunction.prototype%, _sourceText_, |FormalParameters|, |GeneratorBody|, ~non-lexical-this~, _env_, _privateEnv_).
1. Perform SetFunctionName(_closure_, _name_).
- 1. Let _prototype_ be OrdinaryObjectCreate(%GeneratorFunction.prototype.prototype%).
+ 1. Let _prototype_ be OrdinaryObjectCreate(%GeneratorPrototype%).
1. Perform ! DefinePropertyOrThrow(_closure_, *"prototype"*, PropertyDescriptor { [[Value]]: _prototype_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return _closure_.
@@ -23955,7 +24304,7 @@
1. Let _sourceText_ be the source text matched by |GeneratorExpression|.
1. Let _closure_ be OrdinaryFunctionCreate(%GeneratorFunction.prototype%, _sourceText_, |FormalParameters|, |GeneratorBody|, ~non-lexical-this~, _funcEnv_, _privateEnv_).
1. Perform SetFunctionName(_closure_, _name_).
- 1. Let _prototype_ be OrdinaryObjectCreate(%GeneratorFunction.prototype.prototype%).
+ 1. Let _prototype_ be OrdinaryObjectCreate(%GeneratorPrototype%).
1. Perform ! DefinePropertyOrThrow(_closure_, *"prototype"*, PropertyDescriptor { [[Value]]: _prototype_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Perform ! _funcEnv_.InitializeBinding(_name_, _closure_).
1. Return _closure_.
@@ -23986,6 +24335,7 @@ Runtime Semantics: Evaluation
YieldExpression : `yield` `*` AssignmentExpression
1. Let _generatorKind_ be GetGeneratorKind().
+ 1. Assert: _generatorKind_ is either ~sync~ or ~async~.
1. Let _exprRef_ be ? Evaluation of |AssignmentExpression|.
1. Let _value_ be ? GetValue(_exprRef_).
1. Let _iteratorRecord_ be ? GetIterator(_value_, _generatorKind_).
@@ -24015,7 +24365,7 @@ Runtime Semantics: Evaluation
1. Else, set _received_ to Completion(GeneratorYield(_innerResult_)).
1. Else,
1. NOTE: If _iterator_ does not have a `throw` method, this throw is going to terminate the `yield*` loop. But first we need to give _iterator_ a chance to clean up.
- 1. Let _closeCompletion_ be Completion Record { [[Type]]: ~normal~, [[Value]]: ~empty~, [[Target]]: ~empty~ }.
+ 1. Let _closeCompletion_ be NormalCompletion(~empty~).
1. If _generatorKind_ is ~async~, perform ? AsyncIteratorClose(_iteratorRecord_, _closeCompletion_).
1. Else, perform ? IteratorClose(_iteratorRecord_, _closeCompletion_).
1. NOTE: The next step throws a *TypeError* to indicate that there was a `yield*` protocol violation: _iterator_ does not have a `throw` method.
@@ -24024,17 +24374,17 @@ Runtime Semantics: Evaluation
1. Assert: _received_ is a return completion.
1. Let _return_ be ? GetMethod(_iterator_, *"return"*).
1. If _return_ is *undefined*, then
- 1. Set _value_ to _received_.[[Value]].
+ 1. Let _receivedValue_ be _received_.[[Value]].
1. If _generatorKind_ is ~async~, then
- 1. Set _value_ to ? Await(_value_).
- 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _value_, [[Target]]: ~empty~ }.
+ 1. Set _receivedValue_ to ? Await(_receivedValue_).
+ 1. Return ReturnCompletion(_receivedValue_).
1. Let _innerReturnResult_ be ? Call(_return_, _iterator_, « _received_.[[Value]] »).
1. If _generatorKind_ is ~async~, set _innerReturnResult_ to ? Await(_innerReturnResult_).
1. If _innerReturnResult_ is not an Object, throw a *TypeError* exception.
1. Let _done_ be ? IteratorComplete(_innerReturnResult_).
1. If _done_ is *true*, then
- 1. Set _value_ to ? IteratorValue(_innerReturnResult_).
- 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _value_, [[Target]]: ~empty~ }.
+ 1. Let _returnedValue_ be ? IteratorValue(_innerReturnResult_).
+ 1. Return ReturnCompletion(_returnedValue_).
1. If _generatorKind_ is ~async~, set _received_ to Completion(AsyncGeneratorYield(? IteratorValue(_innerReturnResult_))).
1. Else, set _received_ to Completion(GeneratorYield(_innerReturnResult_)).
@@ -24111,10 +24461,11 @@
1. Perform ? FunctionDeclarationInstantiation(_functionObject_, _argumentsList_).
- 1. Let _generator_ be ? OrdinaryCreateFromConstructor(_functionObject_, *"%AsyncGeneratorFunction.prototype.prototype%"*, « [[AsyncGeneratorState]], [[AsyncGeneratorContext]], [[AsyncGeneratorQueue]], [[GeneratorBrand]] »).
+ 1. Let _generator_ be ? OrdinaryCreateFromConstructor(_functionObject_, *"%AsyncGeneratorPrototype%"*, « [[AsyncGeneratorState]], [[AsyncGeneratorContext]], [[AsyncGeneratorQueue]], [[GeneratorBrand]] »).
1. Set _generator_.[[GeneratorBrand]] to ~empty~.
+ 1. Set _generator_.[[AsyncGeneratorState]] to ~suspended-start~.
1. Perform AsyncGeneratorStart(_generator_, |FunctionBody|).
- 1. Return Completion Record { [[Type]]: ~return~, [[Value]]: _generator_, [[Target]]: ~empty~ }.
+ 1. Return ReturnCompletion(_generator_).
@@ -24135,7 +24486,7 @@
1. Let _sourceText_ be the source text matched by |AsyncGeneratorDeclaration|.
1. Let _F_ be OrdinaryFunctionCreate(%AsyncGeneratorFunction.prototype%, _sourceText_, |FormalParameters|, |AsyncGeneratorBody|, ~non-lexical-this~, _env_, _privateEnv_).
1. Perform SetFunctionName(_F_, _name_).
- 1. Let _prototype_ be OrdinaryObjectCreate(%AsyncGeneratorFunction.prototype.prototype%).
+ 1. Let _prototype_ be OrdinaryObjectCreate(%AsyncGeneratorPrototype%).
1. Perform ! DefinePropertyOrThrow(_F_, *"prototype"*, PropertyDescriptor { [[Value]]: _prototype_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return _F_.
@@ -24146,7 +24497,7 @@
1. Let _sourceText_ be the source text matched by |AsyncGeneratorDeclaration|.
1. Let _F_ be OrdinaryFunctionCreate(%AsyncGeneratorFunction.prototype%, _sourceText_, |FormalParameters|, |AsyncGeneratorBody|, ~non-lexical-this~, _env_, _privateEnv_).
1. Perform SetFunctionName(_F_, *"default"*).
- 1. Let _prototype_ be OrdinaryObjectCreate(%AsyncGeneratorFunction.prototype.prototype%).
+ 1. Let _prototype_ be OrdinaryObjectCreate(%AsyncGeneratorPrototype%).
1. Perform ! DefinePropertyOrThrow(_F_, *"prototype"*, PropertyDescriptor { [[Value]]: _prototype_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return _F_.
@@ -24173,7 +24524,7 @@
1. Let _sourceText_ be the source text matched by |AsyncGeneratorExpression|.
1. Let _closure_ be OrdinaryFunctionCreate(%AsyncGeneratorFunction.prototype%, _sourceText_, |FormalParameters|, |AsyncGeneratorBody|, ~non-lexical-this~, _env_, _privateEnv_).
1. Perform SetFunctionName(_closure_, _name_).
- 1. Let _prototype_ be OrdinaryObjectCreate(%AsyncGeneratorFunction.prototype.prototype%).
+ 1. Let _prototype_ be OrdinaryObjectCreate(%AsyncGeneratorPrototype%).
1. Perform ! DefinePropertyOrThrow(_closure_, *"prototype"*, PropertyDescriptor { [[Value]]: _prototype_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Return _closure_.
@@ -24190,7 +24541,7 @@
1. Let _sourceText_ be the source text matched by |AsyncGeneratorExpression|.
1. Let _closure_ be OrdinaryFunctionCreate(%AsyncGeneratorFunction.prototype%, _sourceText_, |FormalParameters|, |AsyncGeneratorBody|, ~non-lexical-this~, _funcEnv_, _privateEnv_).
1. Perform SetFunctionName(_closure_, _name_).
- 1. Let _prototype_ be OrdinaryObjectCreate(%AsyncGeneratorFunction.prototype.prototype%).
+ 1. Let _prototype_ be OrdinaryObjectCreate(%AsyncGeneratorPrototype%).
1. Perform ! DefinePropertyOrThrow(_closure_, *"prototype"*, PropertyDescriptor { [[Value]]: _prototype_, [[Writable]]: *true*, [[Enumerable]]: *false*, [[Configurable]]: *false* }).
1. Perform ! _funcEnv_.InitializeBinding(_name_, _closure_).
1. Return _closure_.
@@ -24452,7 +24803,7 @@ Static Semantics: NonConstructorElements ( ): a List of |ClassElement| Parse
1. Let _list_ be the NonConstructorElements of |ClassElementList|.
1. If the ClassElementKind of |ClassElement| is ~non-constructor-method~, then
- 1. Append |ClassElement| to the end of _list_.
+ 1. Append |ClassElement| to _list_.
1. Return _list_.
@@ -24723,7 +25074,7 @@
Runtime Semantics: EvaluateClassStaticBlockBody (
_functionObject_: an ECMAScript function object,
- ): either a normal completion containing an ECMAScript language value or an abrupt completion
+ ): a return completion or a throw completion
@@ -24731,7 +25082,8 @@
1. Assert: _functionObject_ is a synthetic function created by ClassStaticBlockDefinitionEvaluation step
@@ -24780,6 +25132,7 @@
Runtime Semantics: ClassDefinitionEvaluation (
_classBinding_: a String or *undefined*,
_className_: a property key or a Private Name,
+ _sourceText_: ECMAScript source text,
): either a normal completion containing a function object or an abrupt completion
@@ -24833,7 +25186,7 @@
1. If NewTarget is *undefined*, throw a *TypeError* exception.
1. Let _F_ be the active function object.
1. If _F_.[[ConstructorKind]] is ~derived~, then
- 1. NOTE: This branch behaves similarly to `constructor(...args) { super(...args); }`. The most notable distinction is that while the aforementioned ECMAScript source text observably calls the @@iterator method on `%Array.prototype%`, this function does not.
+ 1. NOTE: This branch behaves similarly to `constructor(...args) { super(...args); }`. The most notable distinction is that while the aforementioned ECMAScript source text observably calls the %Symbol.iterator% method on `%Array.prototype%`, this function does not.
1. Let _func_ be ! _F_.[[GetPrototypeOf]]().
1. If IsConstructor(_func_) is *false*, throw a *TypeError* exception.
1. Let _result_ be ? Construct(_func_, _args_, NewTarget).
@@ -24841,13 +25194,14 @@
1. NOTE: This branch behaves similarly to `constructor() {}`.
1. Let _result_ be ? OrdinaryCreateFromConstructor(NewTarget, *"%Object.prototype%"*).
1. Perform ? InitializeInstanceElements(_result_, _F_).
- 1. Return _result_.
- 1. Let _F_ be CreateBuiltinFunction(_defaultConstructor_, 0, _className_, « [[ConstructorKind]], [[SourceText]] », the current Realm Record, _constructorParent_).
+ 1. Return NormalCompletion(_result_).
+ 1. Let _F_ be CreateBuiltinFunction(_defaultConstructor_, 0, _className_, « [[ConstructorKind]], [[SourceText]], [[PrivateMethods]], [[Fields]] », the current Realm Record, _constructorParent_).
1. Else,
1. Let _constructorInfo_ be ! DefineMethod of _constructor_ with arguments _proto_ and _constructorParent_.
1. Let _F_ be _constructorInfo_.[[Closure]].
1. Perform MakeClassConstructor(_F_).
1. Perform SetFunctionName(_F_, _className_).
+ 1. Set _F_.[[SourceText]] to _sourceText_.
1. Perform MakeConstructor(_F_, *false*, _proto_).
1. If |ClassHeritage| is present, set _F_.[[ConstructorKind]] to ~derived~.
1. Perform ! DefineMethodProperty(_proto_, *"constructor"*, _F_, *false*).
@@ -24913,17 +25267,16 @@
The Symbol Type
The Symbol type is the set of all non-String values that may be used as the key of an Object property (
Each possible Symbol value is unique and immutable.
-Each Symbol value immutably holds an associated value called [[Description]] that is either *undefined* or a String value.
+Each Symbol is unique and immutable.
+Each Symbol has an immutable [[Description]] internal slot whose value is either a String or *undefined*.
Well-Known Symbols
Well-known symbols are built-in Symbol values that are explicitly referenced by algorithms of this specification. They are typically used as the keys of properties whose values serve as extension points of a specification algorithm. Unless otherwise specified, well-known symbols values are shared by all realms (
Within this specification a well-known symbol is referred to by using a notation of the form @@name, where “name” is one of the values listed in
Within this specification a well-known symbol is referred to using the standard
| - Specification Name - | -- [[Description]] - | -- Value and Purpose - | -|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| + Specification Name + | ++ [[Description]] + | ++ Value and Purpose + | +|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@asyncIterator + %Symbol.asyncIterator% | *"Symbol.asyncIterator"* | - A method that returns the default AsyncIterator for an object. Called by the semantics of the `for`-`await`-`of` statement. + A method that returns the default async iterator for an object. Called by the semantics of the `for`-`await`-`of` statement. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@hasInstance + %Symbol.hasInstance% |
*"Symbol.hasInstance"*
@@ -1245,7 +1398,7 @@ Well-Known Symbols | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@isConcatSpreadable + %Symbol.isConcatSpreadable% |
*"Symbol.isConcatSpreadable"*
@@ -1256,18 +1409,18 @@ Well-Known Symbols | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@iterator + %Symbol.iterator% | *"Symbol.iterator"* | - A method that returns the default Iterator for an object. Called by the semantics of the for-of statement. + A method that returns the default iterator for an object. Called by the semantics of the for-of statement. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@match + %Symbol.match% |
*"Symbol.match"*
@@ -1278,18 +1431,18 @@ Well-Known Symbols | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@matchAll + %Symbol.matchAll% | *"Symbol.matchAll"* |
- A regular expression method that returns an iterator, that yields matches of the regular expression against a string. Called by the |
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| - @@replace + %Symbol.replace% |
*"Symbol.replace"*
@@ -1300,7 +1453,7 @@ Well-Known Symbols | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@search + %Symbol.search% |
*"Symbol.search"*
@@ -1311,7 +1464,7 @@ Well-Known Symbols | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@species + %Symbol.species% |
*"Symbol.species"*
@@ -1322,7 +1475,7 @@ Well-Known Symbols | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@split + %Symbol.split% |
*"Symbol.split"*
@@ -1333,7 +1486,7 @@ Well-Known Symbols | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@toPrimitive + %Symbol.toPrimitive% |
*"Symbol.toPrimitive"*
@@ -1344,7 +1497,7 @@ Well-Known Symbols | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@toStringTag + %Symbol.toStringTag% |
*"Symbol.toStringTag"*
@@ -1355,7 +1508,7 @@ Well-Known Symbols | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| - @@unscopables + %Symbol.unscopables% |
*"Symbol.unscopables"*
@@ -1374,20 +1527,22 @@ Numeric TypesECMAScript has two built-in numeric types: Number and BigInt. The following abstract operations are defined over these numeric types. The "Result" column shows the return type, along with an indication if it is possible for some invocations of the operation to return an abrupt completion.
|