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.

Value

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

Examples

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.

Specifications

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

Browser compatibility

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desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
desiredSize

Legend

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Full support
Full support

See also