minnal/server.js

// require Express and Socket.io
var express = require('express');
var app = express();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var path = require('path');
var config = require('./config.js');

// the object that will hold information about the active users currently
// on the site
var visitorsData = {};

app.set('port', (process.env.PORT || 5000));

// serve the static assets (js/dashboard.js and css/dashboard.css)
// from the public/ directory
app.use(express.static(path.join(__dirname, 'public/')));

// serve the index.html page when someone visits any of the following endpoints:
// 1. /
// 2. /about
// 3. /contact
app.get(/\/(about|contact)?$/, function (req, res) {
	res.sendFile(path.join(__dirname, 'views/index.html'));
});

// serve up the dashboard when someone visits /dashboard
app.get('/dashboard', function (req, res) {
	res.sendFile(path.join(__dirname, 'views/dashboard.html'));
});

io.on('connection', function (socket) {
	if (socket.handshake.headers.host === config.host &&
		socket.handshake.headers.referer.indexOf(config.host + config.dashboardEndpoint) > -1) {

		// if someone visits '/dashboard' send them the computed visitor data
		io.emit('updated-stats', computeStats());

	}

	// a user has visited our page - add them to the visitorsData object
	socket.on('visitor-data', function (data) {
		visitorsData[socket.id] = data;
		console.log('New Visitor', visitorsData[socket.id]);

		// compute and send visitor data to the dashboard when a new user visits our page
		io.emit('updated-stats', computeStats());
	});

	socket.on('disconnect', function () {
		// a user has left our page - remove them from the visitorsData object
		console.log('Visitor has left the site', socket.id);
		delete visitorsData[socket.id];

		// compute and send visitor data to the dashboard when a user leaves our page
		io.emit('updated-stats', computeStats());
	});
});

// wrapper function to compute the stats and return a object with the updated stats
function computeStats() {
	return {
		pages: computePageCounts(),
		referrers: computeRefererCounts(),
		activeUsers: getActiveUsers()
	};
}

// get the total number of users on each page of our site
function computePageCounts() {
	// sample data in pageCounts object:
	// { "/": 13, "/about": 5 }
	var pageCounts = {};
	for (var key in visitorsData) {
		var page = visitorsData[key].page;
		if (page in pageCounts) {
			pageCounts[page]++;
		} else {
			pageCounts[page] = 1;
		}
	}
	return pageCounts;
}

// get the total number of users per referring site
function computeRefererCounts() {
	// sample data in referrerCounts object:
	// { "http://twitter.com/": 3, "http://stackoverflow.com/": 6 }
	var referrerCounts = {};
	for (var key in visitorsData) {
		var referringSite = visitorsData[key].referringSite || '(direct)';
		if (referringSite in referrerCounts) {
			referrerCounts[referringSite]++;
		} else {
			referrerCounts[referringSite] = 1;
		}
	}
	return referrerCounts;
}

// get the total active users on our site
function getActiveUsers() {
	return Object.keys(visitorsData).length;
}

http.listen(app.get('port'), function () {
	console.log('listening on *:' + app.get('port'));
});