support-bind-operator

SBO stands for Support the Bind Operator.

Converts value::yourFunction(arg) to yourFunction(value, arg)—but lets your function support either.

Notice: this is the same as sbo from lamansky, but uses fast-path-set instead of lodash.set as lodash.set has a vulnerability.

Installation

npm i support-bind-operator

API

The module exports a single function.

Parameters

1. Optional: Object argument:
   • Optional: arg (integer): The argument index at which this should be inserted. Defaults to 0.
   • Optional: path (string): The dot-separated key path of an options object argument located at index arg into which this should be inserted.
   • Optional: ignoreThis (object, array, or function): this is ignored if ignoreThis strictly equals this, or if ignoreThis is an array containing this, or if ignoreThis is a function which returns true when given this.
2. fn (Function): The function which should receive bind operator support.

Return Value

A wrapper function with bind operator support that calls fn.

Tutorial

Let’s say, for the sake of example, that you have a function called addSuffix:

const addSuffix = (str, suffix) => str + suffix

You use the support-bind-operator module to add support for the bind operator:

const supportBindOperator = require('support-bind-operator')
const addSuffix = supportBindOperator((str, suffix) => str + suffix)

Now your function can be called either the normal way or with the bind operator:

addSuffix('Hello, world', '!') // 'Hello, world!'
'Hello, world'::addSuffix('!') // 'Hello, world!'

Specifying a Parameter Index

Now let’s swap the order of the parameters:

const addSuffix = (suffix, str) => str + suffix

A bound this would now need to become the argument with an index of 1. To do this, pass an extra argument to support-bind-operator:

const supportBindOperator = require('support-bind-operator')
const addSuffix = supportBindOperator({arg: 1}, (suffix, str) => str + suffix)

addSuffix('!', 'Hello, world') // 'Hello, world!'
'Hello, world'::addSuffix('!') // 'Hello, world!'

Specifying an Object Argument Key

Let’s try using a deconstructed object parameter:

const addSuffix = ({str, suffix}) => str + suffix

Do the following to direct a bound this to the str key of the object argument at index zero (i.e. the first, and in this case the only, argument):

const supportBindOperator = require('support-bind-operator')
const addSuffix = supportBindOperator({path: 'str'}, ({str, suffix}) => str + suffix)

addSuffix({str: 'Hello, world', suffix: '!'}) // 'Hello, world!'
'Hello, world'::addSuffix({suffix: '!'}) // 'Hello, world!'

If you have a nested object parameter, you can use a dot-separated key path.