WritableStreamDefaultWriter: 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 May 2022.
Note: This feature is available in Web Workers.
The desiredSize read-only property of the
WritableStreamDefaultWriter 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 is erroring or errored, and 0 if it is closed.
Exceptions
TypeError-
The writer's lock is released.
Examples
js
const writableStream = new WritableStream(
{
write(chunk) {
// …
},
close() {
// …
},
abort(err) {
// …
},
},
queuingStrategy,
);
// …
const writer = writableStream.getWriter();
// …
// return stream's desired size
const size = writer.desiredSize;
Specifications
| Specification |
|---|
| Streams # ref-for-default-writer-desired-size⑥ |