ReadableByteStreamController: enqueue() method

Baseline 2026
Newly available

Since March 2026, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.

Note: This feature is available in Web Workers.

The enqueue() method of the ReadableByteStreamController interface enqueues a given chunk on the associated readable byte stream (the chunk is transferred into the stream's internal queues).

This should only be used to transfer data to the queue when byobRequest is null.

Syntax

js
enqueue(chunk)

Parameters

chunk

The chunk to enqueue.

Return value

None (undefined).

Exceptions

TypeError

Thrown if the source object is not a ReadableByteStreamController, or the stream cannot be read for some other reason, or the chunk is not an object, or the chunk's internal array buffer is non-existent, zero-length, or detached. It is also thrown if the stream has been closed.

Examples

The example in Using readable byte streams > Creating a readable socket push byte stream shows how you can use enqueue() to copy data to the stream if there is no outstanding byobRequest. If there is a byobRequest then it should be used!

The code below shows data being read into an ArrayBuffer using a "hypothetical" socket.readInto() method and then enqueued (but only if data was actually copied):

js
const buffer = new ArrayBuffer(DEFAULT_CHUNK_SIZE);
bytesRead = socket.readInto(buffer, 0, DEFAULT_CHUNK_SIZE);
if (bytesRead === 0) {
  controller.close();
} else {
  controller.enqueue(new Uint8Array(buffer, 0, bytesRead));
}

Specifications

Specification
Streams
# ref-for-rbs-controller-enqueue①

Browser compatibility

desktop mobile server
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Bun
Deno
Node.js
enqueue
Chrome – Full support
Chrome 89 (Release date: 2021-03-02)
footnote Full support
Edge – Full support
Edge 89 (Release date: 2021-03-04)
footnote Full support
Firefox – Full support
Firefox 102 (Release date: 2022-06-28)
footnote Full support
Opera – Full support
Opera 75 (Release date: 2021-03-24)
footnote Full support
Safari – Full support
Safari 26.4 (Release date: 2026-03-24)
footnote Full support
Chrome Android – Full support
Chrome Android 89 (Release date: 2021-03-02)
footnote Full support
Firefox for Android – Full support
Firefox for Android 102 (Release date: 2022-06-28)
footnote Full support
Opera Android – Full support
Opera Android 63 (Release date: 2021-04-16)
footnote Full support
Safari on iOS – Full support
Safari on iOS 26.4 (Release date: 2026-03-24)
footnote Full support
Samsung Internet – Full support
Samsung Internet 15 (Release date: 2021-08-13)
footnote Full support
WebView Android – Full support
WebView Android 89 (Release date: 2021-03-02)
footnote Full support
WebView on iOS – Full support
WebView on iOS 26.4 (Release date: 2026-03-24)
footnote Full support
Bun – Full support
Bun 1 (Release date: 2023-09-08)
footnote Full support
Deno – Full support
Deno 1 (Release date: 2020-05-13)
footnote Full support
Node.js – Full support
Node.js 16.5 (Release date: 2021-07-14)
footnote Full support

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support

See also