ByteLengthQueuingStrategy.size()

The size() method of the ByteLengthQueuingStrategy interface returns the given chunk’s byteLength property.

var size = byteLengthQueuingStrategy.size(chunk);

chunk

A chunk of data being passed through the stream.

An integer representing the byte length of the given chunk.

const queuingStrategy = new ByteLengthQueuingStrategy({ highWaterMark: 1 });

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

var size = queueingStrategy.size(chunk);