I highly recommend reading this: So, what's next?
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.
If you are looking for documentation for obsolete core-js@2, please, check this branch.
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:
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])