Method read

lib/internal/webstreams/readablestream.js:909–945

* @returns {Promise<{ * value : any, * done : boolean * }>}

()

   * }>}
   */
  read() {
    if (!isReadableStreamDefaultReader(this))
      return PromiseReject(new ERR_INVALID_THIS('ReadableStreamDefaultReader'));
    if (this[kState].stream === undefined) {
      return PromiseReject(
        new ERR_INVALID_STATE.TypeError(
          'The reader is not attached to a stream'));
    }

    const stream = this[kState].stream;
    const controller = stream[kState].controller;

    // Fast path: if data is already buffered in a default controller,
    // return a resolved promise immediately without creating a read request.
    // This is spec-compliant because read() returns a Promise, and
    // Promise.resolve() callbacks still run in the microtask queue.
    if (stream[kState].state === 'readable' &&
        isReadableStreamDefaultController(controller) &&
        controller[kState].queue.length > 0) {
      stream[kState].disturbed = true;
      const chunk = dequeueValue(controller);

      if (controller[kState].closeRequested && !controller[kState].queue.length) {
        readableStreamDefaultControllerClearAlgorithms(controller);
        readableStreamClose(stream);
      } else {
        readableStreamDefaultControllerCallPullIfNeeded(controller);
      }

      return PromiseResolve({ done: false, value: chunk });
    }

    // Slow path: create request and go through normal flow
    const readRequest = new DefaultReadRequest();
    readableStreamDefaultReaderRead(this, readRequest);
    return readRequest.promise;
  }

  releaseLock() {
    if (!isReadableStreamDefaultReader(this))