ReadableStreamBYOBReader: cancel() method

{{APIRef("Streams")}}{{AvailableInWorkers}}

The cancel() method of the {{domxref("ReadableStreamBYOBReader")}} interface returns a {{jsxref("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 ({{domxref("ReadableStream.cancel()")}}).

Syntax

cancel()
cancel(reason)

Parameters

• reason {{optional_inline}}
  • : A human-readable reason for the cancellation. The underlying source may or may not use it.

Return value

A {{jsxref("Promise")}}, which fulfills with the value given in the reason parameter.

Exceptions

• {{jsxref("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

{{Specifications}}

Browser compatibility

{{Compat}}

See also

• {{domxref("ReadableStreamBYOBReader.ReadableStreamBYOBReader", "ReadableStreamBYOBReader()")}} constructor
• Using readable byte stream