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.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 newReadableStream
instances. Each of those streams receives the same incoming data.
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 |
---|---|---|
Streams The definition of 'ReadableStream' in that specification. |
Living Standard | Initial definition |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Update compatibility data on GitHub
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
ReadableStream | Chrome Full support 43 | Edge Full support 14 | Firefox
Full support
65
| IE No support No | Opera Full support 30 | Safari ? | WebView Android Full support 43 | Chrome Android Full support 43 | Firefox Android
Full support
65
| Opera Android Full support 30 | Safari iOS ? | Samsung Internet Android Full support 4.0 |
ReadableStream() constructor | Chrome Full support 43 | Edge No support No | Firefox
Full support
65
| IE No support No | Opera Full support 30 | Safari ? | WebView Android Full support 43 | Chrome Android Full support 43 | Firefox Android
Full support
65
| Opera Android Full support 30 | Safari iOS ? | Samsung Internet Android Full support 4.0 |
cancel | Chrome Full support 43 | Edge Full support 14 | Firefox
Full support
65
| IE No support No | Opera Full support 30 | Safari ? | WebView Android Full support 43 | Chrome Android Full support 43 | Firefox Android
Full support
65
| Opera Android Full support 30 | Safari iOS ? | Samsung Internet Android Full support 4.0 |
getReader | Chrome Full support 43 | Edge Full support 14 | Firefox
Full support
65
| IE No support No | Opera Full support 30 | Safari ? | WebView Android Full support 43 | Chrome Android Full support 43 | Firefox Android
Full support
65
| Opera Android Full support 30 | Safari iOS ? | Samsung Internet Android Full support 4.0 |
locked | Chrome Full support 43 | Edge Full support 14 | Firefox
Full support
65
| IE No support No | Opera Full support 30 | Safari ? | WebView Android Full support 43 | Chrome Android Full support 43 | Firefox Android
Full support
65
| Opera Android Full support 30 | Safari iOS ? | Samsung Internet Android Full support 4.0 |
pipeThrough | Chrome Full support 59 | Edge No support No | Firefox No support No | IE No support No | Opera Full support 46 | Safari ? | WebView Android Full support 59 | Chrome Android Full support 59 | Firefox Android No support No | Opera Android Full support 43 | Safari iOS ? | Samsung Internet Android Full support 7.0 |
pipeTo | Chrome Full support 59 | Edge No support No | Firefox No support No | IE No support No | Opera Full support 46 | Safari ? | WebView Android Full support 59 | Chrome Android Full support 59 | Firefox Android No support No | Opera Android Full support 43 | Safari iOS ? | Samsung Internet Android Full support 7.0 |
tee | Chrome Full support 43 | Edge No support No | Firefox
Full support
65
| IE No support No | Opera Full support 30 | Safari ? | WebView Android Full support 43 | Chrome Android Full support 43 | Firefox Android
Full support
65
| Opera Android Full support 30 | Safari iOS ? | Samsung Internet Android Full support 4.0 |
Legend
- Full support
- Full support
- No support
- No support
- Compatibility unknown
- Compatibility unknown
- 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.
See Also
- WHATWG Stream Visualiser, for a basic visualisation of readable, writable, and transform streams.