WritableStreamDefaultWriter.desiredSize

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This page is not complete.

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

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

Syntax

var desiredSize = writableStreamDefaultWriterInstance.desiredSize;

Value

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

The value will be null if the stream cannot be successfully written to (due to either being errored, or having an abort queued up), and zero if the stream is closed.

Exceptions

TypeError
The writer’s lock is released.

Examples

const writableStream = new WritableStream({
  write(chunk) {
    ...
  },
  close() {
    ...
  },
  abort(err) {
    ...
  }
}, queuingStrategy);

...

const writer = writableStream.getWriter();

...

// return stream's desired size
let size = writer.desiredSize;

Specifications

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic support
Experimental
Chrome Full support 59Edge Full support 16Firefox No support NoIE No support NoOpera Full support 46Safari ? WebView Android Full support 59Chrome Android Full support 59Edge Mobile Full support 16Firefox Android No support NoOpera Android Full support 46Safari iOS ? Samsung Internet Android ?

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.

Document Tags and Contributors

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