# core-js
[](#sponsors) [](#backers) [](https://gitter.im/zloirock/core-js?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge) [](https://www.npmjs.com/package/core-js) [](http://npm-stat.com/charts.html?package=core-js&author=&from=2014-11-18) [](https://travis-ci.org/zloirock/core-js) [](https://david-dm.org/zloirock/core-js?type=dev)
> Modular standard library for JavaScript. Includes polyfills for [ECMAScript up to 2019](https://github.com/zloirock/core-js#ecmascript): [promises](https://github.com/zloirock/core-js#ecmascript-promise), [symbols](https://github.com/zloirock/core-js#ecmascript-symbol), [collections](https://github.com/zloirock/core-js#ecmascript-collections), iterators, [typed arrays](https://github.com/zloirock/core-js#ecmascript-typed-arrays), many other features, [ECMAScript proposals](https://github.com/zloirock/core-js#ecmascript-proposals), [some cross-platform WHATWG / W3C features and proposals](#web-standards) like [`URL`](https://github.com/zloirock/core-js#url-and-urlsearchparams). You can load only required features or use it without global namespace pollution.
## As advertising: the author is looking for a good job -)
## [core-js@3, babel and a look into the future](https://github.com/zloirock/core-js/tree/master/docs/2019-03-19-core-js-3-babel-and-a-look-into-the-future.md)
## 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**](https://opencollective.com/core-js) or [**on Patreon**](https://www.patreon.com/zloirock) if you are interested in `core-js`.
---
---
---
[*Example*](http://goo.gl/a2xexl):
```js
import 'core-js'; // <- at the top of your entry point
Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
[1, [2, 3], [4, [5]]].flat(2); // => [1, 2, 3, 4, 5]
Promise.resolve(32).then(x => console.log(x)); // => 32
```
*You can load only required features*:
```js
import 'core-js/features/array/from'; // <- at the top of your entry point
import 'core-js/features/array/flat'; // <- at the top of your entry point
import 'core-js/features/set'; // <- at the top of your entry point
import 'core-js/features/promise'; // <- at the top of your entry point
Array.from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
[1, [2, 3], [4, [5]]].flat(2); // => [1, 2, 3, 4, 5]
Promise.resolve(32).then(x => console.log(x)); // => 32
```
*Or use it without global namespace pollution*:
```js
import from from 'core-js-pure/features/array/from';
import flat from 'core-js-pure/features/array/flat';
import Set from 'core-js-pure/features/set';
import Promise from 'core-js-pure/features/promise';
from(new Set([1, 2, 3, 2, 1])); // => [1, 2, 3]
flat([1, [2, 3], [4, [5]]], 2); // => [1, 2, 3, 4, 5]
Promise.resolve(32).then(x => console.log(x)); // => 32
```
**It's a global version (first 2 examples), for more info see [`core-js` documentation](https://github.com/zloirock/core-js/blob/master/README.md).**