nodejs中的TCP聊天程序求助？

var net=require('net');



var count=0,users={};

var server=net.createServer(function(conn){

    conn.setEncoding('utf-8');

    var nickname;

    conn.write(

        '\n > welcome to node-chat!'

        +'\n > '+ count + ' other people are connected at this time.'

        +'\n > please write your name and press enter:'

    );

    count++;

    conn.on('data',function(data){

        data=data.replace('\r\n','');

        if(!nickname){

            if(users[data]){

                conn.write('>nickname already in use,try again:');

                return;

            }else{

                nickname=data;

                users[nickname]=conn;

                for(var i in users){

                    **users[i].write('>'+ nickname + ' joined the room\n');**

                }

            }

        }    

    });

    conn.on('close',function(){

        count--;

    });

});



server.listen(3000,function(){

    console.log('server listening on *:3000');

});