ReadableStreamDefaultController: desiredSize property
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.
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
A number, or null.
The number can be negative if the queue is over-full. When a custom queuing strategy is used, its chunk sizes can cause the number to have a fractional component. The value is null if the stream has errored and 0 if it is closed.
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 |