js code to realize multi-person chat room

module.exports={
    "port":3000,
    "host":"127.0.0.1"
}

exports.broadcast = function (data, users) {
    var from=data.from;
    var message = data.message;
    message = from+"say: "+message;
    //Build the message var send = {
        mstype:"broadcast",
        message:message
    };
    send = new Buffer(JSON.stringify(send));
    //Traverse all users in the user group, all users on the sender side for(var username in users){
        if(username!=from){
            users[username].write(send);
        }
    }
};

exports.signup = function (socket,data,users) {
//Get the username of the registered user var username=data.username;
    if(!users[username]){ //If it does not exist, save the username and socket
        users[username]=socket;
        var send = {
            mstype:"signup",
            code:1000,
            username:username,
            message: "Registration successful"
        };
        socket.write(JSON.stringify(send));
    }else{//cunzai
        var send = {
            mstype:"signup",
            code:1001,
            message: "The username has been taken, please re-enter the username"
        }
        socket.write(JSON.stringify(send));
    }
};

exports.p2p = function (socket, data, users) {
    var from=data.from;
    var to=data.to;
    var message = data.message;
    var receiver=users[to];
    if(!receiver){//The receiver does not exist var send={
          mstype:"p2p",
          code:2001,
          message: "user"+to+"does not exist"
      }
      socket.write(JSON.stringify(send));
    }else{
        //If it exists, send information to the receiver var send={
            mstype:"p2p",
            code:2000,
            from:from,
            message:from+"to you"+message
        }
        receiver.write(JSON.stringify(send));
    }
};

//p2p chat room server var net=require("net");
var config = require("./config");
var broadcast = require("./broadcast");
var p2p = require("./p2p");
var signup = require("./signup");
var users={};
var server=net.createServer();
server.on ("connection", function (socket) {
    socket.on("data",function (data) {
        data = JSON.parse(data);
        switch (data.mstype) {
            case "signup":
                signup.signup(socket, data, users);
                break;
            case "broadcast":
                broadcast.broadcast(data, users);
                break;
            case "p2p":
                p2p.p2p(socket, data, users);
                break;
            default:
                break;
        }
    });
    socket.on("error",function () {
        console.log("A client exited abnormally");
    });
});
server.listen(config.port,config.host,function () {
    console.log("Server starts listening at port"+config.port+"");
});

var net = require("net");
var config = require("./config");
var Client = net.createConnection({
    port:config.port,
    host:config.host
});
var username;
Client.on("connect",function () {
    console.log("Please enter your username:");
    process.stdin.on("data",function (data){
        data=data.toString().trim();
        // Check if the user already exists if(!username){
            var send = {
                mstype:"signup",
                username:data
            };
            Client.write(JSON.stringify(send));
            return;
        }
        var regex=/(.{1,18}):(.+)/;
        var matches = regex = regex.exec(data);
        if(matches){
            //If it matches, it is p2p
            var from=username;//The sender is yourself var to=matches[1];//To whom is it sent var message=matches[2];
            //Construct JSON format information var send={
                mstype: "p2p",
                from:username,
                to:to,
                message:message
            };
            Client.write(JSON.stringify(send));
        }else{
            //Broadcast var send = {
                mstype:"broadcast",
                from:username,
                message:data
            };
            Client.write(JSON.stringify(send));
        }
    });
});
Client.on("data",function (data) {
    data = JSON.parse(data);
    switch (data.mstype) {
        case "signup":
            var code=data.code;
            switch (code) {
                case 1000:
                    username=data.username;
                    console.log(data.message);
                    break;
                case 1001:
                    console.log(data.message);
                    break;
                default:
                    break;
            }
            break;
        case "broadcast":
            console.log(data.message);
            break;
        case "p2p":
            var code=data.code;
            switch (code) {
                case 2000:
                    console.log(data.message);
                    break;
                case 2001:
                    console.log(data.message);
                    break;
                default:
                    break;
            }
            break;
        default:
            break;
    }
});
Client.on("error",function () {
    console.log("Chat room is closed!!");
})