core-js
Modular standard library for JavaScript. Includes polyfills for ECMAScript 5, 2015, 2016, 2017: promises, symbols, collections, iterators, typed arrays, many other features, ECMAScript proposals, some cross-platform WHATWG / W3C ECMAScript-related features and proposals like setImmediate. You can load only required features or use it without global namespace pollution.
Example:
import 'core-js';
Array.from(new Set([1, 2, 3, 2, 1]));
[1, [2, 3], [4, [5]]].flatten(2);
Promise.resolve(32).then(x => console.log(x));
You can load only required features:
import 'core-js/features/array/from';
import 'core-js/features/array/flatten';
import 'core-js/features/set';
import 'core-js/features/promise';
Array.from(new Set([1, 2, 3, 2, 1]));
[1, [2, 3], [4, [5]]].flatten(2);
Promise.resolve(32).then(x => console.log(x));
Or use it without global namespace pollution:
import from from 'core-js-pure/features/array/from';
import flatten from 'core-js-pure/features/array/flatten';
import Set from 'core-js-pure/features/set';
import Promise from 'core-js-pure/features/promise';
from(new Set([1, 2, 3, 2, 1]));
flatten([1, [2, 3], [4, [5]]], 2);
Promise.resolve(32).then(x => console.log(x));
It's a version without global namespace pollution (the third example), for more info see core-js
documentation.