# web-streams-polyfill Web Streams, based on the WHATWG spec reference implementation. [![build status](https://api.travis-ci.com/MattiasBuelens/web-streams-polyfill.svg?branch=master)](https://travis-ci.com/MattiasBuelens/web-streams-polyfill) [![npm version](https://img.shields.io/npm/v/web-streams-polyfill.svg)](https://www.npmjs.com/package/web-streams-polyfill) [![license](https://img.shields.io/npm/l/web-streams-polyfill.svg)](https://github.com/MattiasBuelens/web-streams-polyfill/blob/master/LICENSE) ## Links - [Official spec][spec] - [Reference implementation][ref-impl] ## Usage This library comes in multiple variants: * `web-streams-polyfill`: a polyfill that replaces the native stream implementations. Recommended for use in web apps supporting older browsers through a ` ``` Usage as a Node module: ```js var streams = require("web-streams-polyfill/ponyfill"); var readable = new streams.ReadableStream(); ``` Usage as a ES2015 module: ```js import { ReadableStream } from "web-streams-polyfill/ponyfill"; const readable = new ReadableStream(); ``` ## Compatibility The `polyfill` and `ponyfill` variants work in any ES5-compatible environment that has a global `Promise`. If you need to support older browsers or Node versions that do not have a native `Promise` implementation (check the [support table][promise-support]), you must first include a `Promise` polyfill (e.g. [promise-polyfill][promise-polyfill]). The `polyfill/es6` and `ponyfill/es6` variants work in any ES2015-compatible environment. The `polyfill/es2018` and `ponyfill/es2018` variants work in any ES2018-compatible environment. [Async iterable support for `ReadableStream`][rs-asynciterator] is available in all variants, but requires an ES2018-compatible environment or a polyfill for `Symbol.asyncIterator`. [`WritableStreamDefaultController.signal`][ws-controller-signal] is available in all variants, but requires a global `AbortController` constructor. If necessary, consider using a polyfill such as [abortcontroller-polyfill]. [Reading with a BYOB reader][mdn-byob-read] is available in all variants, but requires `ArrayBuffer.prototype.transfer()` or `structuredClone()` to exist in order to correctly transfer the given view's buffer. If not available, then the buffer won't be transferred during the read. ## Compliance The polyfill implements [version `4dc123a` (13 Nov 2023)][spec-snapshot] of the streams specification. The polyfill is tested against the same [web platform tests][wpt] that are used by browsers to test their native implementations. The polyfill aims to pass all tests, although it allows some exceptions for practical reasons: * The `es2018` variant passes all of the tests. * The `es6` variant passes the same tests as the `es2018` variant, except for the [test for the prototype of `ReadableStream`'s async iterator][wpt-async-iterator-prototype]. Retrieving the correct `%AsyncIteratorPrototype%` requires using an async generator (`async function* () {}`), which is invalid syntax before ES2018. Instead, the polyfill [creates its own version][stub-async-iterator-prototype] which is functionally equivalent to the real prototype. * The `es5` variant passes the same tests as the `es6` variant, except for various tests about specific characteristics of the constructors, properties and methods. These test failures do not affect the run-time behavior of the polyfill. For example: * The `name` property of down-leveled constructors is incorrect. * The `length` property of down-leveled constructors and methods with optional arguments is incorrect. * Not all properties and methods are correctly marked as non-enumerable. * Down-leveled class methods are not correctly marked as non-constructable. The type definitions are compatible with the built-in stream types of TypeScript 3.3. ## Contributors Thanks to these people for their work on [the original polyfill][creatorrr-polyfill]: - Diwank Singh Tomer ([creatorrr](https://github.com/creatorrr)) - Anders Riutta ([ariutta](https://github.com/ariutta)) [spec]: https://streams.spec.whatwg.org [ref-impl]: https://github.com/whatwg/streams [ponyfill]: https://github.com/sindresorhus/ponyfill [promise-support]: https://kangax.github.io/compat-table/es6/#test-Promise [promise-polyfill]: https://www.npmjs.com/package/promise-polyfill [rs-asynciterator]: https://streams.spec.whatwg.org/#rs-asynciterator [ws-controller-signal]: https://streams.spec.whatwg.org/#ws-default-controller-signal [abortcontroller-polyfill]: https://www.npmjs.com/package/abortcontroller-polyfill [mdn-byob-read]: https://developer.mozilla.org/en-US/docs/Web/API/ReadableStreamBYOBReader/read [spec-snapshot]: https://streams.spec.whatwg.org/commit-snapshots/4dc123a6e7f7ba89a8c6a7975b021156f39cab52/ [wpt]: https://github.com/web-platform-tests/wpt/tree/2a298b616b7c865917d7198a287310881cbfdd8d/streams [wpt-async-iterator-prototype]: https://github.com/web-platform-tests/wpt/blob/2a298b616b7c865917d7198a287310881cbfdd8d/streams/readable-streams/async-iterator.any.js#L24 [stub-async-iterator-prototype]: https://github.com/MattiasBuelens/web-streams-polyfill/blob/v2.0.0/src/target/es5/stub/async-iterator-prototype.ts [creatorrr-polyfill]: https://github.com/creatorrr/web-streams-polyfill

c	File Name	Size	files	T	Date
zip	dist/	9024353	35	---	2025-10-15 10:10:05
zip	es2018/	327	1	---	2025-10-15 10:10:04
zip	es6/	315	1	---	2025-10-15 10:10:04
zip	ponyfill/	840	3	---	2025-10-15 10:10:04
-	LICENSE	1120		%	2025-10-15 10:07:36
-	README.md	6527		md	2025-10-15 10:07:36
-	package.json	2723		json	2025-10-15 10:07:36

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