This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The ReadableStreamDefaultReader
interface of the Streams API represents a default reader that can be used to read stream data supplied from a network (e.g. a fetch request).
Constructor
ReadableStreamDefaultReader()
- Creates and returns a
ReadableStreamDefaultReader()
object instance.
Properties
ReadableStreamDefaultReader.closed
- Allows you to write code that responds to an end to the streaming process. Returns a promise that fulfills if the stream becomes closed or the reader's lock is released, or rejects if the stream errors.
Methods
ReadableStreamDefaultReader.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.
ReadableStreamDefaultReader.read()
- Returns a promise providing access to the next chunk in the stream's internal queue.
ReadableStreamDefaultReader.releaseLock()
- Releases the reader's lock on the stream.
Examples
In the following example, an artifical 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" return 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); }).then(push); }; push(); } }); return new Response(stream, { headers: { "Content-Type": "text/html" } }); });
Specifications
Specification | Status | Comment |
---|---|---|
Streams The definition of 'ReadableStreamDefaultReader' in that specification. |
Living Standard | Initial definition |
Browser Compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support |
52.0 |
57.0 (57.0) | ? |
39 |
? |
Feature | Android Webview | Chrome for Android | Firefox Mobile (Gecko) | Firefox OS | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | 52 | 52 | ? | ? | ? | 39 | ? |
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chrisdavidmills
Last updated by:
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