m

.vscode/settings.json

@@ -0,0 +1,5 @@
+{
+    "cSpell.words": [
+        "unknow"
+    ]
+}

typechallenges/README.md

@@ -1,5 +1,7 @@
 # TypeChallenges
 
+## 使用集合的思想理解 ts
+
 ## keywords
 
 [x] interface
@@ -11,7 +13,9 @@
 [x] object
 [ ] unknown
 
-[ ] never
+[x] never：相当于空集，never 是任何类型的子集
+[x] unknow: 相当于全集，是所有类型的父集
+[x] any: 相当于 unknow 和 never 的结合体，any是所有类型的子集，同时也是所有类型的父集。
 [ ] extends
 [ ] infer
 [ ] namespace/module
@@ -118,3 +122,5 @@ type A = P<never> // string
 
 - [TypeScript 类型挑战](https://github.com/type-challenges/type-challenges)
 - [深入理解 TypeScript](https://jkchao.github.io/typescript-book-chinese/#why)
+- [TS类型体操（一） 基础知识](https://juejin.cn/post/7228833037743915067)
+- [TypeScript 类型体操指北](https://zhuanlan.zhihu.com/p/452657140)

typechallenges/easy/00004-easy-pick.ts

@@ -31,32 +31,31 @@
 
 /* _____________ Your Code Here _____________ */
 
-type MyPick<T, K extends keyof T> = { [P in  K]: T[P]}
-
+type MyPick<T, K extends keyof T> = { [P in K]: T[P] };
 
 /* _____________ Test Cases _____________ */
-import type { Equal, Expect } from '@type-challenges/utils'
+import type { Equal, Expect } from "@type-challenges/utils";
 
 type cases = [
-  Expect<Equal<Expected1, MyPick<Todo, 'title'>>>,
-  Expect<Equal<Expected2, MyPick<Todo, 'title' | 'completed'>>>,
+  Expect<Equal<Expected1, MyPick<Todo, "title">>>,
+  Expect<Equal<Expected2, MyPick<Todo, "title" | "completed">>>,
   // @ts-expect-error
-  MyPick<Todo, 'title' | 'completed' | 'invalid'>,
-]
+  MyPick<Todo, "title" | "completed" | "invalid">
+];
 
 interface Todo {
-  title: string
-  description: string
-  completed: boolean
+  title: string;
+  description: string;
+  completed: boolean;
 }
 
 interface Expected1 {
-  title: string
+  title: string;
 }
 
 interface Expected2 {
-  title: string
-  completed: boolean
+  title: string;
+  completed: boolean;
 }
 
 /* _____________ Further Steps _____________ */

typechallenges/easy/00007-easy-readonly.ts

@@ -0,0 +1,55 @@
+/*
+  7 - Readonly
+  -------
+  by Anthony Fu (@antfu) #easy #built-in #readonly #object-keys
+
+  ### Question
+
+  Implement the built-in `Readonly<T>` generic without using it.
+
+  Constructs a type with all properties of T set to readonly, meaning the properties of the constructed type cannot be reassigned.
+
+  For example:
+
+  ```ts
+  interface Todo {
+    title: string
+    description: string
+  }
+
+  const todo: MyReadonly<Todo> = {
+    title: "Hey",
+    description: "foobar"
+  }
+
+  todo.title = "Hello" // Error: cannot reassign a readonly property
+  todo.description = "barFoo" // Error: cannot reassign a readonly property
+  ```
+
+  > View on GitHub: https://tsch.js.org/7
+*/
+
+/* _____________ Your Code Here _____________ */
+
+type MyReadonly<T> = { readonly [P in keyof T]: T[P] };
+
+/* _____________ Test Cases _____________ */
+import type { Equal, Expect } from "@type-challenges/utils";
+
+type cases = [Expect<Equal<MyReadonly<Todo1>, Readonly<Todo1>>>];
+
+interface Todo1 {
+  title: string;
+  description: string;
+  completed: boolean;
+  meta: {
+    author: string;
+  };
+}
+
+/* _____________ Further Steps _____________ */
+/*
+  > Share your solutions: https://tsch.js.org/7/answer
+  > View solutions: https://tsch.js.org/7/solutions
+  > More Challenges: https://tsch.js.org
+*/

typechallenges/easy/00011-easy-tuple-to-object.ts

@@ -0,0 +1,54 @@
+/*
+  11 - Tuple to Object
+  -------
+  by sinoon (@sinoon) #easy #object-keys
+
+  ### Question
+
+  Given an array, transform it into an object type and the key/value must be in the provided array.
+
+  For example:
+
+  ```ts
+  const tuple = ['tesla', 'model 3', 'model X', 'model Y'] as const
+
+  type result = TupleToObject<typeof tuple> // expected { 'tesla': 'tesla', 'model 3': 'model 3', 'model X': 'model X', 'model Y': 'model Y'}
+  ```
+
+  > View on GitHub: https://tsch.js.org/11
+*/
+
+/* _____________ Your Code Here _____________ */
+
+type TupleToObject<T extends readonly any[]> = {[P in T[number]] : P}
+
+
+
+/* _____________ Test Cases _____________ */
+import type { Equal, Expect } from '@type-challenges/utils'
+
+const tuple = ['tesla', 'model 3', 'model X', 'model Y'] as const
+const tupleNumber = [1, 2, 3, 4] as const
+const sym1 = Symbol(1)
+const sym2 = Symbol(2)
+const tupleSymbol = [sym1, sym2] as const
+const tupleMix = [1, '2', 3, '4', sym1] as const
+
+type t = TupleToObject<typeof tupleNumber>
+
+type cases = [
+  Expect<Equal<TupleToObject<typeof tuple>, { 'tesla': 'tesla', 'model 3': 'model 3', 'model X': 'model X', 'model Y': 'model Y' }>>,
+  Expect<Equal<TupleToObject<typeof tupleNumber>, { 1: 1, 2: 2, 3: 3, 4: 4 }>>,
+  Expect<Equal<TupleToObject<typeof tupleSymbol>, { [sym1]: typeof sym1, [sym2]: typeof sym2 }>>,
+  Expect<Equal<TupleToObject<typeof tupleMix>, { 1: 1, '2': '2', 3: 3, '4': '4', [sym1]: typeof sym1 }>>,
+]
+
+// @ts-expect-error
+type error = TupleToObject<[[1, 2], {}]>
+
+/* _____________ Further Steps _____________ */
+/*
+  > Share your solutions: https://tsch.js.org/11/answer
+  > View solutions: https://tsch.js.org/11/solutions
+  > More Challenges: https://tsch.js.org
+*/

typechallenges/easy/00014-easy-first-of-array.ts

@@ -0,0 +1,53 @@
+/*
+  14 - First of Array
+  -------
+  by Anthony Fu (@antfu) #easy #array
+
+  ### Question
+
+  Implement a generic `First<T>` that takes an Array `T` and returns its first element's type.
+
+  For example:
+
+  ```ts
+  type arr1 = ['a', 'b', 'c']
+  type arr2 = [3, 2, 1]
+
+  type head1 = First<arr1> // expected to be 'a'
+  type head2 = First<arr2> // expected to be 3
+  ```
+
+  > View on GitHub: https://tsch.js.org/14
+*/
+
+/* _____________ Your Code Here _____________ */
+
+// type First<T extends any[]> = T extends [] ? never : T[0];
+// type First<T extends any[]> = T["length"] extends 0 ? never : T[0];
+type First<T extends any[]> = T extends { length: 0 } ? never : T[0];
+
+type f = First<[]>;
+
+/* _____________ Test Cases _____________ */
+import type { Equal, Expect } from "@type-challenges/utils";
+
+type cases = [
+  Expect<Equal<First<[3, 2, 1]>, 3>>,
+  Expect<Equal<First<[() => 123, { a: string }]>, () => 123>>,
+  Expect<Equal<First<[]>, never>>,
+  Expect<Equal<First<[undefined]>, undefined>>
+];
+
+type errors = [
+  // @ts-expect-error
+  First<"notArray">,
+  // @ts-expect-error
+  First<{ 0: "arrayLike" }>
+];
+
+/* _____________ Further Steps _____________ */
+/*
+  > Share your solutions: https://tsch.js.org/14/answer
+  > View solutions: https://tsch.js.org/14/solutions
+  > More Challenges: https://tsch.js.org
+*/

typechallenges/easy/00018-easy-length-of-tuple.ts

@@ -0,0 +1,49 @@
+/*
+  18 - Length of Tuple
+  -------
+  by sinoon (@sinoon) #easy #tuple
+
+  ### Question
+
+  For given a tuple, you need create a generic `Length`, pick the length of the tuple
+
+  For example:
+
+  ```ts
+  type tesla = ['tesla', 'model 3', 'model X', 'model Y']
+  type spaceX = ['FALCON 9', 'FALCON HEAVY', 'DRAGON', 'STARSHIP', 'HUMAN SPACEFLIGHT']
+
+  type teslaLength = Length<tesla>  // expected 4
+  type spaceXLength = Length<spaceX> // expected 5
+  ```
+
+  > View on GitHub: https://tsch.js.org/18
+*/
+
+/* _____________ Your Code Here _____________ */
+
+type Length<T> = T extends {length: number} ? never : T["length"];
+
+type z = Length<5>
+
+/* _____________ Test Cases _____________ */
+import type { Equal, Expect } from '@type-challenges/utils'
+
+const tesla = ['tesla', 'model 3', 'model X', 'model Y'] as const
+const spaceX = ['FALCON 9', 'FALCON HEAVY', 'DRAGON', 'STARSHIP', 'HUMAN SPACEFLIGHT'] as const
+
+type cases = [
+  Expect<Equal<Length<typeof tesla>, 4>>,
+  Expect<Equal<Length<typeof spaceX>, 5>>,
+  // @ts-expect-error
+  Length<5>,
+  // @ts-expect-error
+  Length<'hello world'>,
+]
+
+/* _____________ Further Steps _____________ */
+/*
+  > Share your solutions: https://tsch.js.org/18/answer
+  > View solutions: https://tsch.js.org/18/solutions
+  > More Challenges: https://tsch.js.org
+*/