node.js引入net模块，建立tcp服务器，写一个聊天室

var net = require("net");

var count = 0;
var user = {};//存储用户
// 创建tcp服务器
var server = net.createServer(function(socket){
    socket.write(`now have ${count} at this node chat ,please say your name \r\n`);
    count++;
    var nickname;//临时存储用户名字
    //公共广播方法
    function broadcast(msg){
        for(var i in user){
            if(i!=nickname){
                user[i].write(msg);
            }
        }
    }
    var temp="";
    socket.on("data",function(data){
        temp+=data;//将输入的字符拼接
        data = temp.replace(/\r|\n/g,"");//检测如果用户回车操作。替换掉
        if(temp.indexOf("\n")===-1){//判断是否有回车，如果有则结束，没有的话return继续拼接
            return;
        };
        if(!nickname){
            if(user[data]){//用户名存在的时候
            socket.rwite(`name has been used ,please try other\r\n`);
            temp="";
            return
            }else{
                nickname=data;
                user[nickname] = socket;//此处socket不明白，说是一个链接
                broadcast(`${nickname} join the chat\r\n`);
            }
        }
        else{
            broadcast(`${nickname} say: ${data}\r\n`)
        }
        temp="";40     });
    socket.on("close",function(){//用户离开
        count--;
        delete user[nickname];
        broadcast(`${nickname} leave the room\r\n`)
    })
});
server.listen(9000,function(){
    console.log("running on 9000");
})