W3cubDocs

/Web APIs

CountQueuingStrategy

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨January 2019⁩.

Note: This feature is available in Web Workers.

The CountQueuingStrategy interface of the Streams API provides a built-in chunk counting queuing strategy that can be used when constructing streams.

Constructor

CountQueuingStrategy(): Creates a new CountQueuingStrategy object instance.

Instance properties

CountQueuingStrategy.highWaterMark Read only: The total number of chunks that can be contained in the internal queue before backpressure is applied.

Instance methods

CountQueuingStrategy.size(): Always returns 1.

Examples

const queueingStrategy = new CountQueuingStrategy({ highWaterMark: 1 });

const writableStream = new WritableStream(
  {
    // Implement the sink
    write(chunk) {
      // …
    },
    close() {
      // …
    },
    abort(err) {
      console.log("Sink error:", err);
    },
  },
  queueingStrategy,
);

const size = queueingStrategy.size();

Specifications

Specification
Streams> # cqs-class>

Browser compatibility

	Desktop					Mobile
	Chrome	Edge	Firefox	Opera	Safari	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	WebView Android	WebView on iOS
`CountQueuingStrategy`	52	16	65	39	10.1	52	65	41	10.3	6.0	52	10.3
`CountQueuingStrategy`	52	16	65	39	10.1	52	65	41	10.3	6.0	52	10.3
`highWaterMark`	52	16	65	39	10.1	52	65	41	10.3	6.0	52	10.3
`size`	52	16	65	39	10.1	52	65	41	10.3	6.0	52	10.3