The core-js-pure package is a version of core-js that doesn't pollute the global namespace. It provides polyfills for ECMAScript features, including promises, symbols, collections, iterators, typed arrays, and many other features that are part of the ECMAScript specification but may not be available in all JavaScript environments.

What are core-js-pure's main functionalities?

Polyfilling Promises

This code sample demonstrates how to polyfill Promises using core-js-pure. It allows you to use Promises in environments where they are not natively supported.

import 'core-js-pure/stable/promise';

const promise = Promise.resolve(42);
promise.then(value => console.log(value));

Polyfilling Array methods

This code sample shows how to polyfill Array.prototype.find method. It enables the use of this method in environments where it is not part of the Array prototype.

import 'core-js-pure/stable/array/find';

const array = [1, 2, 3];
const found = array.find(item => item > 1);
console.log(found); // 2

Polyfilling Object static methods

This code sample illustrates how to polyfill Object.assign method. It allows the merging of multiple source objects into a target object in environments that do not support this method natively.

import 'core-js-pure/stable/object/assign';

const target = { a: 1 };
const source = { b: 2 };
const returnedTarget = Object.assign(target, source);

console.log(returnedTarget); // { a: 1, b: 2 }

Polyfilling String methods

This code sample demonstrates how to polyfill String.prototype.includes method. It provides a way to check if one string may be found within another string, returning true or false as appropriate.

import 'core-js-pure/stable/string/includes';

const string = 'hello world';
const includesHello = string.includes('hello');
console.log(includesHello); // true

Other packages similar to core-js-pure

Changelog

Source

3.37.1 - 2024.05.14

Changes v3.37.0...v3.37.1
Fixed URL.parse feature detection for some specific cases
Compat data improvements:
- Set methods proposal added and marked as supported from FF 127
- Symbol.dispose added and marked as supported from V8 ~ Chromium 125
- Math.f16round and DataView.prototype.{ getFloat16, setFloat16 } added and marked as supported from Deno 1.43
- URL.parse added and marked as supported from Chromium 126
- URL.parse added and marked as supported from NodeJS 22.0
- URL.parse added and marked as supported from Deno 1.43
- Added Rhino 1.7.15 compat data, many features marked as supported
- Added NodeJS 22.0 compat data mapping
- Added Deno 1.43 compat data mapping
- Added Electron 31 compat data mapping
- Updated Opera Android 82 compat data mapping
- Added Samsung Internet 26 compat data mapping
- Added Oculus Quest Browser 33 compat data mapping

Readme

Source

logo

Modular standard library for JavaScript. Includes polyfills for ECMAScript up to 2023: promises, symbols, collections, iterators, typed arrays, many other features, ECMAScript proposals, some cross-platform WHATWG / W3C features and proposals like URL. You can load only required features or use it without global namespace pollution.

Raising funds

core-js isn't backed by a company, so the future of this project depends on you. Become a sponsor or a backer if you are interested in core-js: Open Collective, Patreon, Boosty, Bitcoin ( bc1qlea7544qtsmj2rayg0lthvza9fau63ux0fstcz ), Alipay.

Example of usage:

import 'core-js/actual';

Promise.resolve(42).then(it => console.log(it)); // => 42

Array.from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]

[1, 2].flatMap(it => [it, it]); // => [1, 1, 2, 2]

(function * (i) { while (true) yield i++; })(1)
  .drop(1).take(5)
  .filter(it => it % 2)
  .map(it => it ** 2)
  .toArray(); // => [9, 25]

structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])

You can load only required features:

import 'core-js/actual/promise';
import 'core-js/actual/set';
import 'core-js/actual/iterator';
import 'core-js/actual/array/from';
import 'core-js/actual/array/flat-map';
import 'core-js/actual/structured-clone';

Promise.resolve(42).then(it => console.log(it)); // => 42

Array.from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]

[1, 2].flatMap(it => [it, it]); // => [1, 1, 2, 2]

(function * (i) { while (true) yield i++; })(1)
  .drop(1).take(5)
  .filter(it => it % 2)
  .map(it => it ** 2)
  .toArray(); // => [9, 25]

structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])

Or use it without global namespace pollution:

import Promise from 'core-js-pure/actual/promise';
import Set from 'core-js-pure/actual/set';
import Iterator from 'core-js-pure/actual/iterator';
import from from 'core-js-pure/actual/array/from';
import flatMap from 'core-js-pure/actual/array/flat-map';
import structuredClone from 'core-js-pure/actual/structured-clone';

Promise.resolve(42).then(it => console.log(it)); // => 42

from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]

flatMap([1, 2], it => [it, it]); // => [1, 1, 2, 2]

Iterator.from(function * (i) { while (true) yield i++; }(1))
  .drop(1).take(5)
  .filter(it => it % 2)
  .map(it => it ** 2)
  .toArray(); // => [9, 25]

structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])

It's a version without global namespace pollution (the third example), for more info see core-js documentation.

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Package last updated on 14 May 2024

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