core-js
As advertising: the author is looking for a good job :)
core-js@3, babel and a look into the future
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 on Open Collective or on Patreon if you are interested in core-js.
It's documentation for obsolete core-js@2. If you looking documentation for actual core-js version, please, check this branch.
Modular standard library for JavaScript. Includes polyfills for ECMAScript 5, ECMAScript 6: promises, symbols, collections, iterators, typed arrays, ECMAScript 7+ proposals, setImmediate, etc. Some additional features such as dictionaries or extended partial application. You can require only needed features or use it without global namespace pollution.
Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
'*'.repeat(10); // => '**********'
Promise.resolve(32).then(x => console.log(x)); // => 32
setImmediate(x => console.log(x), 42); // => 42
Without global namespace pollution:
var core = require('core-js/library'); // With a modular system, otherwise use global `core`
core.Array.from(new core.Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
core.String.repeat('*', 10); // => '**********'
core.Promise.resolve(32).then(x => console.log(x)); // => 32
core.setImmediate(x => console.log(x), 42); // => 42
Index
- Usage
- Supported engines
- Features
- Missing polyfills
- Changelog
Usage
Basic
npm i core-js
bower install core.js
// Default
require('core-js');
// Without global namespace pollution
var core = require('core-js/library');
// Shim only
require('core-js/shim');
If you need complete build for browser, use builds from core-js/client path:
- default: Includes all features, standard and non-standard.
- as a library: Like "default", but does not pollute the global namespace (see 2nd example at the top).
- shim only: Only includes the standard methods.
Warning: if you use core-js with the extension of native objects, require all needed core-js modules at the beginning of entry point of your application, otherwise, conflicts may occur.
CommonJS
You can require only needed modules.
require('core-js/fn/set');
require('core-js/fn/array/from');
require('core-js/fn/array/find-index');
Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
[1, 2, NaN, 3, 4].findIndex(isNaN); // => 2
// or, w/o global namespace pollution:
var Set = require('core-js/library/fn/set');
var from = require('core-js/library/fn/array/from');
var findIndex = require('core-js/library/fn/array/find-index');
from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
findIndex([1, 2, NaN, 3, 4], isNaN); // => 2
Available entry points for methods / constructors, as above examples, and namespaces: for example, core-js/es6/array (core-js/library/es6/array) contains all [ES6 `Arra
