Simplechat Server

// Made by djazz
// This is a chat server for node.js
// See demo at http://djazz.mine.nu:8004/

var http = require('http');
var fs = require('fs');

var loadFile = function (filename, mime, res) {
    fs.readFile(filename, function (err, data) {
        if(err) throw err;
        res.writeHead(200, {'Content-Type': mime});
        res.end(data);
    });
};

var server = http.createServer(function (request, response) {
    switch(request.url) {
        case '/':
            loadFile(__dirname+'/index.html', 'text/html', response);
            break;
        case '/script.js':
            loadFile(__dirname+'/script.js', 'application/javascript', response);
            break;
        case '/style.css':
            loadFile(__dirname+'/style.css', 'text/css', response);
            break;
        default:
            response.writeHead(404, {'Content-Type': 'text/plain'});
            response.end('Not found');
            break;
    }
});
server.listen(8004, function () {
    console.log(timestamp(), 'Chatroom server started');
});
var io = require('socket.io').listen(server);
io.set('log level', 1);

var uid = 0;

var users = {};
var usernameExists = function (username) {
    for(var i in users) {
        if(users.hasOwnProperty(i) && users[i].name === username) return true;
    }
    return false;
};
var timestamp = function () {
    var now = new Date();
    var h = now.getHours();
    var m = now.getMinutes();
    var s = now.getSeconds();
    return (h>9?h:'0'+h)+"."+(m>9?m:'0'+m)+"."+(s>9?s:'0'+s);
};

io.sockets.on('connection', function (socket) {
    socket.uid = uid++;
    socket.on('message', function (message) {
        if(socket.uid > -1) {
            message = message.replace(/\</g, '&lt;').replace(/\>/g, '&gt;');
            io.sockets.emit('message', {'message': message, 'index': socket.uid});
            console.log(timestamp(), users[socket.uid].name+':', message);
        }
    });
    socket.on('join', function (username) {
        username = username.trim().substring(0, 32);
        if(usernameExists(username)) {
            var i=2;
            while(usernameExists(username+i)) {
                i+=1;
            }
            username += i;
        }
        username = username.replace(/\</g, '&lt;').replace(/\>/g, '&gt;');
        users[socket.uid] = {name: username};
        socket.broadcast.emit('join', {'index': socket.uid, name: username});
        socket.emit('userlist', users);
        console.log(timestamp(), username+" joined");
    });
    socket.on('disconnect', function () {
        if(users[socket.uid] !== undefined) {
            console.log(timestamp(), (users[socket.uid].name)+" left");
            socket.broadcast.emit('left', socket.uid);
            delete users[socket.uid];
        }
    });
});