Node.js http.ClientRequest 'upgrade'事件用法及代码示例

事件：'upgrade'

参数

• response <http.IncomingMessage>
• socket <stream.Duplex>
• head <Buffer>

每次服务器响应升级请求时发出。如果未侦听此事件且响应状态代码为 101 Switching Protocols，则接收到升级标头的客户端将关闭其连接。

除非用户指定 <net.Socket> 以外的套接字类型，否则此事件保证会传递 <net.Socket> 类的实例，该类是 <stream.Duplex> 的子类。

演示如何侦听 'upgrade' 事件的客户端服务器对。

const http = require('node:http');

// Create an HTTP server
const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('okay');
});
server.on('upgrade', (req, socket, head) => {
  socket.write('HTTP/1.1 101 Web Socket Protocol Handshake\r\n' +
               'Upgrade: WebSocket\r\n' +
               'Connection: Upgrade\r\n' +
               '\r\n');

  socket.pipe(socket); // echo back
});

// Now that server is running
server.listen(1337, '127.0.0.1', () => {

  // make a request
  const options = {
    port: 1337,
    host: '127.0.0.1',
    headers: {
      'Connection': 'Upgrade',
      'Upgrade': 'websocket'
    }
  };

  const req = http.request(options);
  req.end();

  req.on('upgrade', (res, socket, upgradeHead) => {
    console.log('got upgraded!');
    socket.end();
    process.exit(0);
  });
});