io.sockets.in（room）.emit（）无法正常工作

Question

由于某种原因，当我想向给定房间的插座发出信号时，我什么也没得到。但是，当我仅向一个特定的套接字发出信号时，它确实起作用。这是我的代码：

//client side
var socket = io();
var room = "abc";
startButton.onclick = function(){
    socket.emit('startGame',{room:room});
}

socket.on('startGameResponse', function(msg){
    console.log(msg);
});

//server side
var serv = require('http').Server(app);
var io = require('socket.io')(serv,{});

io.sockets.on('connection', function(socket){

socket.on('startGame',function(data){
    var room = data.room;
    socket.join(room);

    io.sockets.in(room).emit('startGameResponse','player joined');

}