ByteLengthQueuingStrategy()

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

Syntax

new ByteLengthQueuingStrategy(highWaterMark)

Parameters

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 the highWaterMark parameter specifies a simple count of the number of chunks, with ByteLengthQueuingStrategy(), the highWaterMark parameter 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

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 Standard
# blqs-constructor

Browser compatibility

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