求助：socket.io搭建聊天室的时候报错？求大神帮助。

就是这篇文章（http://cnodejs.org/topic/531ed0f0fb2070fd4702d5ef）上的demo，我运行取来之后，输入用户名准备连接的时候出错，出错位置如下： /Users/pro/Desktop/ChatApp-master/node_modules/socket.io/lib/transports/websocket.js:33 else transport = new protocolVersions['default'](mng, data, req); ^ TypeError: undefined is not a function at new WebSocket (/Users/pro/Desktop/ChatApp-master/node_modules/socket.io/lib/transports/websocket.js:33:20) at Manager.handleClient (/Users/pro/Desktop/ChatApp-master/node_modules/socket.io/lib/manager.js:662:19) at Manager.handleUpgrade (/Users/pro/Desktop/ChatApp-master/node_modules/socket.io/lib/manager.js:618:8) at Server. (/Users/pro/Desktop/ChatApp-master/node_modules/socket.io/lib/manager.js:123:10) at Server.EventEmitter.emit (events.js:106:17) at Socket.socket.ondata (http.js:1986:14) at TCP.onread (net.js:525:27)

运行环境： mac10.9 nodejs v0.10.22 Firefox 27.0.1

ps:本来开始是能够运行的，后来不知道怎么地就再也不能连接了。