server.js

/* eslint-disable no-console */
'use-strict';

const app = require('./app'),
	debug = require('debug')('app:server'),
	http = require('http');

//Normalize a port into a number, string, or false.
var normalizePort = (val) => {
	var port = parseInt(val, 10);

	if (isNaN(port)) {
		// named pipe
		return val;
	}

	if (port >= 0) {
		// port number
		return port;
	}

	return false;
};

//Event listener for HTTP server "error" event.
var onError = (error) => {
	if (error.syscall !== 'listen') {
		throw error;
	}

	var bind = typeof port === 'string'
		? 'Pipe ' + port
		: 'Port ' + port;

	// handle specific listen errors with friendly messages
	switch (error.code) {
	case 'EACCES':
		console.error(bind + ' requires elevated privileges');
		process.exit(1);
		break;
	case 'EADDRINUSE':
		console.error(bind + ' is already in use');
		process.exit(1);
		break;
	default:
		throw error;
	}
};

//Event listener for HTTP server "listening" event.
var onListening = () => {
	var addr = server.address();
	var bind = typeof addr === 'string'
		? 'pipe ' + addr
		: 'port ' + addr.port;
	debug('Listening on ' + bind);
};

//Get port from environment and store in Express.
var port = normalizePort(process.env.PORT || '5000');
app.set('port', port);


// Create HTTP server.
var server = http.createServer(app);
var io = require('socket.io')(server);
app.set('socketio', io);

// Listen on provided port, on all network interfaces.
server.listen(port);
server.on('error', onError);
server.on('listening', onListening);