app.js

var app = require('http').createServer(handler)
    , io = require('socket.io').listen(app)
    , fs = require('fs')

var config = require('./settings.js')

app.listen(config.port);

function handler (req, res) {
    fs.readFile(__dirname + '/index.html',
        function (err, data) {
            if (err) {
                res.writeHead(500);
                return res.end('Error loading index.html');
            }

            res.writeHead(200);
            res.end(data);
        });
}

var user_sockets = {}

function sendTo(userName, message, data) {
    console.log('sending to: ' + userName)
    console.log(user_sockets)
    for (var i=0; i < user_sockets[userName].length; i++) {
        var socket = io.sockets.socket(user_sockets[userName][i]);
        if(socket) {
            socket.emit(message, data);
        }
    }
}

io.sockets.on('connection', function (socket) {
    socket.on('set name', function(data) {
        if(!user_sockets[data.name]) {
            user_sockets[data.name] = [];
        }
        user_sockets[data.name].push(socket.id);
    });
    socket.on('start edit', function (data) {
        socket.broadcast.emit('started edit', data);
    });
    socket.on('request edit', function (data) {
        sendTo(data.currently_editing_user, 'request edit', data);
    });
    socket.on('edit request response pending', function(data) {
        sendTo(data.requester_user, 'edit request response pending', data);
    });
    socket.on('edit request response', function(data) {
        sendTo(data.requester_user, 'edit request response', data);
        sendTo(data.currently_editing_user, 'edit response sent on another window', data);
    });
    socket.on('disconnect', function () {
        for(var name in user_sockets) {
            var currentLength = user_sockets.length;
            while(currentLength--) {
                if(user_sockets[name][currentLength] === socket.id) {
                    user_sockets[name].splice(currentLength, 1);
                }
            }
        }
    });
});