ReadableStreamDefaultController: desiredSize property

Note: This feature is available in Web Workers.

The desiredSize read-only property of the ReadableStreamDefaultController interface returns the desired size required to fill the stream's internal queue.


An integer. Note that this can be negative if the queue is over-full.


The A readable stream with an underlying push source and backpressure support example in the spec provides a good example of using desiredSize to manually detect when the stream is full and apply backpressure, and also of using ReadablestreamDefaultController.error() to manually trigger a stream error if another part of the system it relies on fails.


Streams Standard
# ref-for-rs-default-controller-desired-size②

Browser compatibility

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See also