server.js

var express = require('express');
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io').listen(server);

app.get('/', function(req, res) {
    res.sendfile(__dirname + '/index.html');
});
app.use('/public', express.static(__dirname + '/public'));

server.listen(80);

io.sockets.on('connection', function(socket) {
    socket.broadcast.emit('status', { message: 'Someone connected' });

    socket.on('send', function(data) {
        socket.get('name', function(err, name) {
            socket.broadcast.emit('receive', { message: data.message, user: name });
        });
    });

    socket.on('set name', function(data) {
        socket.set('name', data.name);

        socket.broadcast.emit('status', { message: 'Someone is now known as ' + data.name });
        socket.emit('status', { message: 'You are now known as ' + data.name });
    });

    socket.on('disconnect', function() {
        socket.get('name', function(err, name) {
            name = (name === null ? 'Someone' : name);
            socket.broadcast.emit('status', { message: name + ' disconnected' });
        });
    });
});