ReadableStreamBYOBReader: ReadableStreamBYOBReader() constructor
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 ReadableStreamBYOBReader() constructor creates and returns a ReadableStreamBYOBReader object instance.
Note:
You generally wouldn't use this constructor manually;
instead, you'd use the ReadableStream.getReader() method with the argument "byob".
Syntax
new ReadableStreamBYOBReader(stream)
Parameters
stream-
The
ReadableStreamto be read.
Return value
An instance of the ReadableStreamBYOBReader object.
Exceptions
TypeError-
Thrown if the supplied
streamparameter is not aReadableStream, or it is already locked for reading by another reader, or its stream controller is not aReadableByteStreamController.
Examples
The constructor is rarely called directly.
Instead call ReadableStream.getReader() as shown:
const reader = stream.getReader({ mode: "byob" });
Specifications
| Specification |
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| Streams # ref-for-byob-reader-constructor① |
Browser compatibility
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ReadableStreamBYOBReader() constructor
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