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


var desiredSize = readableStreamDefaultControllerInstance.desiredSize;


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.


Specification Status Comment
The definition of 'desiredSize' in that specification.
Living Standard Initial definition.

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 Contributors to this page: chrisdavidmills
 Last updated by: chrisdavidmills,