nodejs发送udp广播还是蛮简单的，我们先写个服务器用于接收广播数据，代码如下：

var server = dgram.createSocket(\"udp4\");

server.on(\"error\", function (err) {
  console.log(\"server error:\\n\" + err.stack);
  server.close();
});

server.on(\"message\", function (msg, rinfo) {
  console.log(\"server got: \" + msg + \" from \" +
    rinfo.address + \":\" + rinfo.port);
});

server.on(\"listening\", function () {
  var address = server.address();
  console.log(\"server listening \" +
      address.address + \":\" + address.port);
});

server.bind(41234);