A simple chat on node.js. Based on Ryan Dahl presentation example (http://www.youtube.com/watch?v=jo_B4LTHi3I)

node-chat.js

var net = require('net')

var users = (function() {

    var users = []

    return {

        add: function(socket) {

            var user = new User(this, socket)
            users.push(user)

            user.sendOthers("# User joined\n")

            return user
        },

        remove: function(user) {

            var i = users.indexOf(user)
            if (i == -1) throw "User not found"

            user.sendOthers("# User left\n")

            users.splice(i, 1)
        },

        all: function() {
            return users
        }
    }
})()

var User = function(users, socket) {

    return {

        sendOthers: function(message) {
            var _users = users.all()
            for (var i = 0; i < _users.length; i++) {
                if (_users[i] == this) continue
                _users[i].send(message)
            }
        },

        send: function(message) {
            socket.write(message)
        },

        leave: function() {
            users.remove(this)
        }
    }
}

net.createServer(function(socket) {

    var user = users.add(socket)

    socket.on('data', function(data) {
        user.sendOthers("> " + data)
    })

    socket.on('close', function(hadError) {
        user.leave()
    })

}).listen(8000)