Creating Socket.IO Server using Express Generator

const createError = require('http-errors');
const express = require('express');
const path = require('path');
const cookieParser = require('cookie-parser');
const logger = require('morgan');
const http = require("http");
const socketio = require("socket.io");
const app = express();

const indexRouter = require('./routes/index');
const usersRouter = require('./routes/users');

// Create the http server
const server = require('http').createServer(app);

// Create the Socket IO server on
// the top of http server
const io = socketio(server);

// View engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'hbs');

app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', indexRouter);
app.use('/users', usersRouter);

// Catch 404 and forward to error handler
app.use(function (req, res, next) {
    next(createError(404));
});

// Error handler
app.use(function (err, req, res, next) {

    // Set locals, only providing error
    // in development
    res.locals.message = err.message;
    res.locals.error = req.app.get('env')
        === 'development' ? err : {};

    // render the error page
    res.status(err.status || 500);
    res.render('error');
});

module.exports = { app: app, server: server };

#!/usr/bin/env node

// Module dependencies
const app = require('../app').app;
const debug = require('debug')('socketiotest:server');
const http = require('http');

// Get port from environment and store in Express
const port = normalizePort(process.env.PORT || '3000');
app.set('port', port);

// Create HTTP server
const server = require("../app").server;

// Listen on provided port, on all
// network interfaces.

server.listen(port);
server.on('error', onError);
server.on('listening', onListening);

// Normalize a port into a number,
// string, or false.
function normalizePort(val) {
    let 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
function onError(error) {
    if (error.syscall !== 'listen') {
        throw error;
    }

    let 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.
function onListening() {
    let addr = server.address();
    let bind = typeof addr === 'string'
        ? 'pipe ' + addr
        : 'port ' + addr.port;
    debug('Listening on ' + bind);
}