ReadableStreamBYOBReader: cancel() method

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Note: This feature is available in Web Workers.

The cancel() method of the ReadableStreamBYOBReader interface returns a Promise that resolves when the stream is canceled. Calling this method signals a loss of interest in the stream by a consumer.

Note: If the reader is active, the cancel() method behaves the same as that for the associated stream (ReadableStream.cancel()).

Syntax

js
cancel()
cancel(reason)

Parameters

reason Optional

A human-readable reason for the cancellation. The underlying source may or may not use it.

Return value

A Promise, which fulfills with the value given in the reason parameter.

Exceptions

TypeError

The source object is not a ReadableStreamBYOBReader, or the stream has no owner.

Examples

This example code calls the cancel() method when a button is pressed, passing the string "user choice" as a reason. The promise resolves when cancellation completes.

js
button.addEventListener("click", () => {
  reader.cancel("user choice").then(() => console.log(`cancel complete`));
});

Note that this code can be seen running in the Using readable byte streams example code (press the Cancel stream button).

Specifications

Specification
Streams
# ref-for-generic-reader-cancel②

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
cancel

Legend

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

Full support
Full support
No support
No support

See also