Responding in Streaming Mode

async function handleRequest(request) {
  const response = await fetch('https://static.cloudcachetci.com/qcloud/main/scripts/release/common/vendors/jquery-3.2.1.min.js');

  if (response.status !== 200) {
    return response;
  }

  // Generate readable streams and writeable streams.
  const { readable, writable } = new TransformStream();
  // Respond to the client in streaming mode.
  response.body.pipeTo(writable);

  return new Response(readable, response);
}

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