How to stream OpenAI responses to browser in real-time?

app.get('/chat-stream', async ({ query: { prompt } }, res) => {
  res.set('Content-Type', 'text/event-stream');
  const stream = await openai.chat.completions.create({
    model: 'gpt-4o-mini',
    messages: [{ role: 'user', content: prompt }],
    stream: true
  });
  for await (const chunk of stream) {
    res.write(`data: ${JSON.stringify(chunk)}\n\n`);
  }
});