ByteLengthQueuingStrategy: ByteLengthQueuingStrategy() constructor

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 ByteLengthQueuingStrategy() constructor creates and returns a ByteLengthQueuingStrategy object instance.

Syntax

js
new ByteLengthQueuingStrategy(options)

Parameters

options

An object with the following property:

highWaterMark

The total number of bytes that can be contained in the internal queue before backpressure is applied.

Unlike CountQueuingStrategy() where highWaterMark specifies a simple count of the number of chunks, with ByteLengthQueuingStrategy(), highWaterMark specifies a number of bytes — specifically, given a stream of chunks, how many bytes worth of those chunks (rather than a count of how many of those chunks) can be contained in the internal queue before backpressure is applied.

Return value

An instance of the ByteLengthQueuingStrategy object.

Exceptions

None.

Examples

js
const queuingStrategy = new ByteLengthQueuingStrategy({
  highWaterMark: 1 * 1024,
});

const readableStream = new ReadableStream(
  {
    start(controller) {
      // …
    },
    pull(controller) {
      // …
    },
    cancel(err) {
      console.log("stream error:", err);
    },
  },
  queuingStrategy,
);

const size = queuingStrategy.size(chunk);

Specifications

Specification
Streams
# blqs-constructor

Browser compatibility

See also