JavaScript SSE服务器推送

const eventSource = new EventSource('/api/sse');

eventSource.onmessage = function(event) {
  console.log('收到消息:', event.data);
  // 更新页面内容
  document.getElementById('output').innerText += event.data + '\n';
};

eventSource.onerror = function(event) {
  console.error('SSE连接出错', event);
  // 浏览器会自动尝试重连
};

app.get('/api/sse', (req, res) => {
  res.writeHead(200, {
    'Content-Type': 'text/event-stream',
    'Cache-Control': 'no-cache',
    'Connection': 'keep-alive'
  });

  // 每隔3秒推送一条消息
  const interval = setInterval(() => {
    const data = { time: new Date().toISOString() };
    res.write(`data: ${JSON.stringify(data)}\n\n`);
  }, 3000);

  // 客户端断开时清理资源
  req.on('close', () => {
    clearInterval(interval);
    res.end();
  });
});

res.write('event: notification\ndata: {"msg": "新消息提醒"}\nid: 101\n\n');

eventSource.addEventListener('notification', function(event) {
  console.log('收到通知:', event.data);
});