Combine Data in Streaming Mode

In this example, an Edge Function fetches and merges multiple resources, then serves the combined stream to a client.

Code

const RESOURCE_URLS = [
  'https://data.playground.edgeone.ai/api/user/1',
  'https://data.playground.edgeone.ai/api/user/2',
];

async function combine(resources, writable) {
  for (const resource of resources) {
    await resource.pipeTo(writable, {
      preventClose: true
    });
  }

  const writer = writable.getWriter();
  writer.close();
  writer.releaseLock();
}

async function handleRequest() {
  const requests = RESOURCE_URLS.map(url => fetch(url));

  const responses = await Promise.all(requests);
  const videos = responses.map(res => res.body);

  const { readable, writable } = new TransformStream();
  combine(videos, writable);

  return new Response(readable);
}

addEventListener('fetch', event => {
  event.respondWith(handleRequest(event.request));
});

Preview

References

• Runtime APIs: TransformStream
• Runtime APIs: Response