Web/API/ReadableStream

The ReadableStream interface of the Streams API represents a readable stream of byte data. The Fetch API offers a concrete instance of a ReadableStream through the body property of a Response object.

Constructor

ReadableStream(): Creates and returns a readable stream object from the given handlers.

Properties

ReadableStream.locked Read only: The locked getter returns whether or not the readable stream is locked to a reader.

Methods

ReadableStream.cancel(): Cancels the stream, signaling a loss of interest in the stream by a consumer. The supplied reason argument will be given to the underlying source, which may or may not use it.

ReadableStream.getIterator(): Creates a ReadableStream async iterator instance and locks the stream to it. While the stream is locked, no other reader can be acquired until this one is released.

ReadableStream.getReader(): Creates a reader and locks the stream to it. While the stream is locked, no other reader can be acquired until this one is released.
ReadableStream.pipeThrough(): Provides a chainable way of piping the current stream through a transform stream or any other writable/readable pair.
ReadableStream.pipeTo(): Pipes the current ReadableStream to a given WritableStream and returns a promise that fulfills when the piping process completes successfully, or rejects if any errors were encountered.
ReadableStream.tee(): The tee method tees this readable stream, returning a two-element array containing the two resulting branches as new ReadableStream instances. Each of those streams receives the same incoming data.
[[ReadableStream%5b%40%40asyncIterator%5d.html|ReadableStream[@@asyncIterator]()]]: Alias of getIterator method.

Examples

In the following example, an artificial Response is created to stream HTML fragments fetched from another resource to the browser.

It demonstrates the usage of a ReadableStream in combination with a Uint8Array.

fetch("https://www.example.org/").then((response) => {
  const reader = response.body.getReader();
  const stream = new ReadableStream({
    start(controller) {
      // The following function handles each data chunk
      function push() {
        // "done" is a Boolean and value a "Uint8Array"
        reader.read().then(({ done, value }) => {
          // Is there no more data to read?
          if (done) {
            // Tell the browser that we have finished sending data
            controller.close();
            return;
          }

          // Get the data and send it to the browser via the controller
          controller.enqueue(value);
          push();
        });
      };
      
      push();
    }
  });

  return new Response(stream, { headers: { "Content-Type": "text/html" } });
});

Specifications

Specification	Status	Comment
StreamsThe definition of 'ReadableStream' in that specification.	Living Standard	Initial definition

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`ReadableStream` Experimental'	Chrome Full support 43	Edge Full support 14	Firefox Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE No support No	Opera Full support 30	Safari Full support 10.1	WebView Android Full support 43	Chrome Android Full support 43	Firefox Android Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android Full support 30	Safari iOS Full support 10.3	Samsung Internet Android Full support 4.0
`ReadableStream()` constructor Experimental'	Chrome Full support 43	Edge Full support 79	Firefox Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE No support No	Opera Full support 30	Safari Full support 10.1	WebView Android Full support 43	Chrome Android Full support 43	Firefox Android Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android Full support 30	Safari iOS Full support 10.3	Samsung Internet Android Full support 4.0
`cancel` Experimental'	Chrome Full support 43	Edge Full support 14	Firefox Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE No support No	Opera Full support 30	Safari Full support 10.1	WebView Android Full support 43	Chrome Android Full support 43	Firefox Android Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android Full support 30	Safari iOS Full support 10.3	Samsung Internet Android Full support 4.0
`getReader` Experimental'	Chrome Full support 43	Edge Full support 14	Firefox Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE No support No	Opera Full support 30	Safari Full support 10.1	WebView Android Full support 43	Chrome Android Full support 43	Firefox Android Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android Full support 30	Safari iOS Full support 10.3	Samsung Internet Android Full support 4.0
`locked` Experimental'	Chrome Full support 43	Edge Full support 14	Firefox Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE No support No	Opera Full support 30	Safari Full support 10.1	WebView Android Full support 43	Chrome Android Full support 43	Firefox Android Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android Full support 30	Safari iOS Full support 10.3	Samsung Internet Android Full support 4.0
`pipeThrough` Experimental'	Chrome Full support 59	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 46	Safari Full support 10.1	WebView Android Full support 59	Chrome Android Full support 59	Firefox Android No support No	Opera Android Full support 43	Safari iOS Full support 10.3	Samsung Internet Android Full support 7.0
`pipeTo` Experimental'	Chrome Full support 59	Edge Full support 79	Firefox No support No	IE No support No	Opera Full support 46	Safari Full support 10.1	WebView Android Full support 59	Chrome Android Full support 59	Firefox Android No support No	Opera Android Full support 43	Safari iOS Full support 10.3	Samsung Internet Android Full support 7.0
`tee` Experimental'	Chrome Full support 43	Edge Full support 79	Firefox Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	IE No support No	Opera Full support 30	Safari Full support 10.1	WebView Android Full support 43	Chrome Android Full support 43	Firefox Android Full support 65 Full support 65 Full support 57 Disabled' Disabled' From version 57: this feature is behind the `dom.streams.enabled` preference (needs to be set to `true`) and the `javascript.options.streams` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android Full support 30	Safari iOS Full support 10.3	Samsung Internet Android Full support 4.0

Legend

Full support: Full support
No support: No support
Experimental. Expect behavior to change in the future.': Experimental. Expect behavior to change in the future.
User must explicitly enable this feature.': User must explicitly enable this feature.