server.js

var express = require('express');
var passport = require('passport');
var Strategy = require('passport-facebook').Strategy;

var config = require('./config/OAuth').facebook;
var PORT = require('./config/env').PORT;

passport.use(
  new Strategy(
    {
      clientID: config.clientID,
      clientSecret: config.clientSecret,
      callbackURL: config.callbackURL
    },
    function(accessToken, refreshToken, profile, cb) {
      return cb(null, profile);
    }
  )
);

passport.serializeUser(function(user, cb) {
  cb(null, user);
});

passport.deserializeUser(function(obj, cb) {
  cb(null, obj);
});

// Create a new Express application.
var app = express();

// Configure view engine to render EJS templates.
app.set('views', __dirname + '/views');
app.set('view engine', 'ejs');

// Use application-level middleware for common functionality, including
// logging, parsing, and session handling.
app.use(require('morgan')('combined'));
app.use(require('cookie-parser')());
app.use(require('body-parser').urlencoded({ extended: true }));
app.use(
  require('express-session')({
    secret: 'keyboard cat',
    resave: true,
    saveUninitialized: true
  })
);

// Initialize Passport and restore authentication state, if any, from the
// session.
app.use(passport.initialize());
app.use(passport.session());

// Define routes.
app.get('/', function(req, res) {
  res.render('home', { user: req.user });
});

app.get('/login', function(req, res) {
  res.render('login');
});

app.get('/login/facebook', passport.authenticate('facebook'));

app.get(
  '/login/facebook/return',
  passport.authenticate('facebook', {
    failureRedirect: '/login',
    scope: ['user_likes']
  }),
  function(req, res) {
    res.redirect('/');
  }
);

app.get('/profile', require('connect-ensure-login').ensureLoggedIn(), function(req,res) {
  res.render('profile', { user: req.user, app_id: config.clientID, PORT: PORT });
});

app.listen(PORT, () =>{
    console.log(`Listening on PORT  ${PORT}`)
});