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

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.

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);