cancel(reason)

import { ReadableStream } from 'k6/experimental/streams';
import { setTimeout } from 'k6/timers';

export default async function () {
  // Define a number stream that emits numbers from 1 to 10 every second
  const stream = numbersStream();
  const reader = stream.getReader();

  while (true) {
    const { done, value } = await reader.read();
    if (done) break;

    if (value === 8) {
      // Cancel the stream when the number is 8, any enqueued chunks are lost
      await reader.cancel('cancelling the stream');
      break;
    }
  }
}

function numbersStream() {
  let currentNumber = 0;

  return new ReadableStream({
    start(controller) {
      const fn = () => {
        if (currentNumber < 10) {
          controller.enqueue(++currentNumber);
          setTimeout(fn, 1000);
          return;
        }

        controller.close();
      };
      setTimeout(fn, 1000);
    },
  });
}