login and signup page mongodb

var express = require("express"), 
    mongoose = require("mongoose"), 
    passport = require("passport"), 
    bodyParser = require("body-parser"), 
    LocalStrategy = require("passport-local"), 
    passportLocalMongoose =  
        require("passport-local-mongoose"), 
    User = require("./models/user"); 
  
mongoose.set('useNewUrlParser', true); 
mongoose.set('useFindAndModify', false); 
mongoose.set('useCreateIndex', true); 
mongoose.set('useUnifiedTopology', true); 
mongoose.connect("mongodb://localhost/auth_demo_app"); 
  
var app = express(); 
app.set("view engine", "ejs"); 
app.use(bodyParser.urlencoded({ extended: true })); 
  
app.use(require("express-session")({ 
    secret: "Rusty is a dog", 
    resave: false, 
    saveUninitialized: false
})); 
  
app.use(passport.initialize()); 
app.use(passport.session()); 
  
passport.use(new LocalStrategy(User.authenticate())); 
passport.serializeUser(User.serializeUser()); 
passport.deserializeUser(User.deserializeUser()); 
  
//===================== 
// ROUTES 
//===================== 
  
// Showing home page 
app.get("/", function (req, res) { 
    res.render("home"); 
}); 
  
// Showing secret page 
app.get("/secret", isLoggedIn, function (req, res) { 
    res.render("secret"); 
}); 
  
// Showing register form 
app.get("/register", function (req, res) { 
    res.render("register"); 
}); 
  
// Handling user signup 
app.post("/register", function (req, res) { 
    var username = req.body.username 
    var password = req.body.password 
    User.register(new User({ username: username }), 
            password, function (err, user) { 
        if (err) { 
            console.log(err); 
            return res.render("register"); 
        } 
  
        passport.authenticate("local")( 
            req, res, function () { 
            res.render("secret"); 
        }); 
    }); 
}); 
  
//Showing login form 
app.get("/login", function (req, res) { 
    res.render("login"); 
}); 
  
//Handling user login 
app.post("/login", passport.authenticate("local", { 
    successRedirect: "/secret", 
    failureRedirect: "/login"
}), function (req, res) { 
}); 
  
//Handling user logout  
app.get("/logout", function (req, res) { 
    req.logout(); 
    res.redirect("/"); 
}); 
  
function isLoggedIn(req, res, next) { 
    if (req.isAuthenticated()) return next(); 
    res.redirect("/login"); 
} 
  
var port = process.env.PORT || 3000; 
app.listen(port, function () { 
    console.log("Server Has Started!"); 
});