call-bind

What is call-bind?

The call-bind npm package is a utility that allows you to use the ECMAScript 5 .call and .apply methods with a fixed this value. It is particularly useful when you want to ensure that the context (the this value) of a function call is bound to a specific object, regardless of how the function is invoked. This can be helpful in functional programming and when dealing with higher-order functions that might change the context of a function call.

What are call-bind's main functionalities?

callBind

Provides a way to use the native call method in a bound fashion, ensuring the this value is fixed when invoking a function.

const callBind = require('call-bind');
const call = callBind.call;
const unboundSlice = Array.prototype.slice;
const slice = call(unboundSlice);

function example() {
  const args = slice(arguments);
  console.log(args);
}

example(1, 2, 3); // Logs: [1, 2, 3]

applyBind

Allows you to use the native apply method in a bound manner, similar to callBind but for functions that expect an array of arguments.

const callBind = require('call-bind');
const apply = callBind.apply;
const unboundForEach = Array.prototype.forEach;
const forEach = apply(unboundForEach);

function example(array, callback) {
  forEach(array, callback);
}

example([1, 2, 3], function(element) { console.log(element); }); // Logs: 1, 2, 3

Other packages similar to call-bind

function-bind

Implements the Function.prototype.bind method in an ECMAScript 5-compliant way. It is similar to call-bind in that it allows you to fix the this value for function calls, but it does so by returning a new function with the this value bound, rather than using the call or apply methods directly.

README

call-bind

Robustly .call.bind() a function.

Getting started

npm install --save call-bind

Usage/Examples

const assert = require('assert');
const callBind = require('call-bind');
const callBound = require('call-bind/callBound');

function f(a, b) {
	assert.equal(this, 1);
	assert.equal(a, 2);
	assert.equal(b, 3);
	assert.equal(arguments.length, 2);
}

const fBound = callBind(f);

const slice = callBound('Array.prototype.slice');

delete Function.prototype.call;
delete Function.prototype.bind;

fBound(1, 2, 3);

assert.deepEqual(slice([1, 2, 3, 4], 1, -1), [2, 3]);

Tests

Clone the repo, npm install, and run npm test

Changelog

v1.0.8 - 2024-12-05

Commits

• [Refactor] extract out some helpers and avoid get-intrinsic usage 407fd5e
• [Refactor] replace code with extracted call-bind-apply-helpers 81018fb
• [Tests] use set-function-length/env 0fc311d
• [actions] split out node 10-20, and 20+ 77a0cad
• [Dev Deps] update @ljharb/eslint-config, auto-changelog, es-value-fixtures, gopd, object-inspect, tape a145d10
• [Tests] replace aud with npm audit 30ca3dd
• [Deps] update set-function-length 57c79a3
• [Dev Deps] add missing peer dep 601cfa5