core-jsJavaScript 的模块化标准库

core-js 是 babel-polyfill 的底层依赖，通过各种奇技淫巧，用 ES3 实现了大部分的 ES2017 原生标准库，同时还要严格遵循规范。

Example of usage：

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

没有全域命名空间污染：

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

经过测试并支持的平台

• Chrome 26+

• Firefox 4+

• Safari 5+

• Opera 12+

• Internet Explorer 6+ (sure, IE8- with ES3 limitations)

• Edge

• Android Browser 2.3+

• iOS Safari 5.1+

• PhantomJS 1.9 / 2.1

• NodeJS 0.8+