Pure node simple websocket proxy

proxy.ts

function setupWsProxy(server: http.Server) {
  server.on('upgrade', (clientReq, clientSocket) => {
    const req_ = http.request({
      port: remotePort,
      host: remoteHost,
      headers: clientReq.headers
    })
    req_.end()

    req_.on('upgrade', (remoteResponse, remoteSocket) => {
      const head_ = [
        'HTTP/1.1 101 Switching Protocols',
        ...Object.entries(remoteResponse.headers).map(([key, value]) => `${key}: ${value}`),
        ''
      ]
        .map((line) => line.concat('\r\n'))
        .join('')

      clientSocket.write(head_)
      clientSocket.pipe(remoteSocket)
      remoteSocket.pipe(clientSocket)
    })
  })
}