Streams

// webstreams.mjs
const numbers = ReadableStream.from([1, 2, 3, 4]);
const doubled = numbers.pipeThrough(
  new TransformStream({
    transform(n, controller) {
      controller.enqueue(n * 2);
    },
  }),
);

const seen = [];
await doubled.pipeTo(
  new WritableStream({
    write(n) {
      seen.push(n);
    },
  }),
);
console.log(seen.join(" "));

const text = await new Response(ReadableStream.from(["he", "llo"]).pipeThrough(new TextEncoderStream())).text();
console.log(text);

2 4 6 8
hello