ReadableStreamBYOBReader: cancel() 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 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
cancel()
cancel(reason)
Parameters
reasonOptional-
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.
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
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| Streams # ref-for-generic-reader-cancel② |
Browser compatibility
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Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
See also
ReadableStreamBYOBReader()constructor- Using readable byte stream