Web Streams API

• ReadableStream: source (fetch response.body, file, generator)
• WritableStream: destination (fetch POST body, WebSocket)
• TransformStream: middle stage (decode, encrypt, compress)
• Pipe: reader.pipeThrough(transformer).pipeTo(writer)
• Backpressure: built-in, slow consumer does not overwhelm producer

// Stream fetch response
const response = await fetch('/api/llm-chat');
const reader = response.body.getReader();
const decoder = new TextDecoder();
while (true) {
  const { done, value } = await reader.read();
  if (done) break;
  output.textContent += decoder.decode(value);
}

// TransformStream — decrypt on-the-fly
const decryptor = new TransformStream({
  transform(chunk, ctl) { ctl.enqueue(decrypt(chunk)); }
});

• Streaming SSR
• Edge Runtime