node.txt

npm init

npm install express 


create a file name it (app.js)

-------Basic node hello world----------

const express = require('express');
const app = express()
const PORT = 5000

app.get('/',(req,res)=> {
    res.send("Hello world")
})

app.listen(PORT,()=>{
    console.log("Server is running",PORT)
})



--------To Run-------------- 

node app(filename)

autorestart server nodemon
or install nodemon

npm install nodemon -g

after that 

nodemon app(filename)

-------------MIDDLEWARE-------------

create a MIDDLEWARE


const express = require('express');
const app = express()
const PORT = 5000


const customeMiddleware = () => {
    console.log(middleware executed)
}

app.use(customeMiddleware)

app.get('/',(req,res)=> {
    res.send("Hello world")
})

app.listen(PORT,()=>{
    console.log("Server is running",PORT)
})


-------------Setup MIDDLEWARE-------------

setup a MIDDLEWARE

const express = require('express');
const app = express()
const PORT = 5000


const customeMiddleware = (req,res,next) => {
    console.log("middleware executed")
    next()
}

app.use(customeMiddleware)

app.get('/',(req,res)=> {
    console.log("Home")
    res.send("Hello world")
})

app.listen(PORT,()=>{
    console.log("Server is running",PORT)
})


-------------Custom MIDDLEWARE-------------

Setup  for any one function



const express = require('express');
const app = express()
const PORT = 5000


const customeMiddleware = (req,res,next) => {
    console.log("middleware executed")
    next()
}

app.get('/',(req,res)=> {
    console.log("Home")
    res.send("Hello world")
})

app.get('/about',customeMiddleware,(req,res)=> {
    console.log("Home")
    res.send("Hello world")
})

app.listen(PORT,()=>{
    console.log("Server is running",PORT)
})



-------------Setup mongoDB-----------------

create a file keys.js(filename)

module.exports={
    MONGOURI:" link of the mongodb "
}

install mongoose

npm install mongoose


const express = require('express');
const app = express()
const mongoose = require('mongoose')
const PORT = 5000
const{MONGOURI}= require("./keys.js")


mongoose.connect(MONGOURI,{
    useNewUrlParser:true,
    useunifiedTopology: true
})
mongoose.connection.on('connected',()=>{
    console.log("Connected to mongo")
})
mongoose.connection.on('error',(err)=>{
    console.log("error connecting",err)
})


app.listen(PORT,()=>{
    console.log("Server is running",PORT)
})



------------------------------------------ PART 2 SIMPLE LOGIN PROJECT ----------------------------------------------------

npm init

npm i express ejs bcrypt

npm i --save-dev nodemon dotenv

create file
.gitignore

type
.env
node_modules

on package.json

scripts: {
    "devstart": "nodemon server.js"

}


to start 
npm run devstart



create a file server.js

type
const express = require('express')
const app = express()

app.set('view-engine','ejs')

app.get('/', (req,res) => {
    res.render('index.ejs',{ name: 'aravind' })
})

app.listen(3000)



-----------views-------------
create folder views

create file index.ejs

<h1>hi <%= name %> </h1>

create another file register.ejs

create another file login.ejs



add get route in server.js


const express = require('express')
const app = express()

app.set('view-engine','ejs')

app.get('/', (req,res) => {
    res.render('index.ejs',{ name: req.user.name })
})
app.get('/login', (req,res) => {
    res.render('login.ejs')
})
app.get('/register', (req,res) => {
    res.render('register.ejs')
})



app.listen(3000)



NOw design the page 

go to register.ejs
<h1> Register </h1>
<form action="/register" method="POST">
<div>
    <label for="name">NAME</label>
    <input type="text" id="name" name="name" required>
    <label for="name">NAME</label>
    <input type="text" id="name" name="name" required> 
    <label for="name">NAME</label>
    <input type="text" id="name" name="name" required>

    <button type="submit">Register</submit>
</div>
</form>
<a href="/login">login</a> 



Design same for login(Copy and set)




Add line on server.js

app.post('/login',(req,res)=> {

})

app.post('/register',(req,res)=> {

})



under app.set
type
app.use(express.urlencoded({ extended: false}))


now for saving in local variable 
create empty array in top
const users = []

add bcrypt for passwrd at header
const bcrypt = require('bcrypt')

now verify register 

app.post('/register', async (req,res)=> {
    try{
        const hashedpassword = await bcrypt.hash(req.body.password, 10 )
        users.push({
            id = Date.now().toString(),
            name = req.body.name,
            name = req.body.name,
            name = req.body.name,
            password = hashedpassword
        })
        res.redirect('/login')  
    }catch{
        res.redirect('/register')
    }
       console.log(users)    <================= To check if the data are being fetched or not
})



install passport
npm i passport passport-local express-session express-flash



create a passport config file

create file passport-config.js

type
const LocalStrategy = require('passport-local').Strategy
const bcrypt =require('bcrypt')

function initialize(passport, getUserByEmail, getUserByID) {

    const authenticateUser = async (email , password, done) => {
        const user = getUserByEmail(email)
        if (user == null) {
            return done(null, false , { message: "user error no email id found"}
        }
        try {
            if (await bcrypt.compare(password, user.password)) {
                return done(null, user)
            } else {
                return done(null , false , {message: "password incorrect"})
            }
        } catch (e){
            return done(e)
        }
    }
    passport.use(new LocalStrategy({ usernameField: 'email' },
    authenticateUser))
    passport.serializeUser((user,done)=> done(null,user.id))
    passport.deserializeUser((id,done)=> {
       return done(null,getUserByID(id))
        })

}
module.exports = initialize



in server.js

const passport = require('passport')

const initializePassport = require('./passport-config')
initializePassport(passport, 
    email => users.find(user => user.email === email),
    id => users.find(user => user.id === id)

)



adding flash

const flash = require('express-flash')
const session = require('express-session')

under express.urlencoded
app.use(flash())
app.use(session({
    secret: process.env.SESSION_SECRET,
    resave: false,
    saveUninitialized: false
}))
app.use(passport.initialize())
app.use(passport.session())



Now in dot env file

SESSION_SECRET = secret


in server.js header

if (process.env.NODE_ENV !== 'prodcution') {
    require('dotenv').config()
}



now in server.js

(change)
app.post('/login', passport.authenticate('local', {
    successRedirect: '/',
    failureRedirect: '/login'
    failureFlash: true
}))


in login.ejs

on top
<% if(messages.error) { %>
<%= messages.error %>
<% } %>


to stay away from error messages

in server.js

secondlast line

function checkAuthenticated(req,res,next) => {
    if(req.isAuthenticated()){
        return next()
    }
    res.redirect('/login')
}


(change)
app.get('/', checkAuthenticated, (req,res) => {
    res.render('index.ejs',{ name: req.user.name })
})


function checkNotAuthenticated(req,res,next) => {
    if(req.isAuthenticated()){
        return res.redirect('/')
    }
    next()
}   

(change)
app.get('/login', checkNotAuthenticated, (req,res) => {
    res.render('login.ejs')
})


(change)
app.post('/login', checkNotAuthenticated, passport.authenticate('local', {
    successRedirect: '/',
    failureRedirect: '/login'
    failureFlash: true
}))

app.get('/register', checkNotAuthenticated, (req,res) => {
    res.render('register.ejs')
})

app.post('/register', checkNotAuthenticated, async (req,res)=> {
    try{
        const hashedpassword = await bcrypt.hash(req.body.password, 10 )
        users.push({
            id = Date.now().toString(),
            name = req.body.name,
            name = req.body.name,
            name = req.body.name,
            password = hashedpassword
        })
        res.redirect('/login')  
    }catch{
        res.redirect('/register')
    }
       console.log(users)    <================= To check if the data are being fetched or not
})


--Logout structure--

in server.js before function

app.delete('/logout',(req,res)=>{
    req.logOut()
    res.redirect('/login')
})

install package 
npm i method-override

on top add header

const methodOverride = require('method-override')

under use clause
app.use(methodOverride('_method'))

under index.ejs
<form action="/logout?_method=DELETE" method="POST">
    <button type="submit">Log Out </button> 
</form>