For cookies based auth in MERN

react_client.js

import React, {useState} from 'react'
import axios from 'axios'

export default function Image() {
    axios.defaults.baseURL = http://localhost:5000

    const [User, setUser] = useState({);
    
    const handleSubmit = (e) => {
      e.preventDefault();
      
      axios.post(`/register`,User,{withCredentials: true})
        .then(res =>{
            console.log("register success")
        })
        .catch(err => {
            console.log(err)
        })
    };
    return (
        <form onSubmit={handleSubmit}>
          <input type="name" name="name" onChange={e=>setUser({...User, name: e.target.value })} value={User.name} required />
          <input type="email" name="email" onChange={e=>setUser({...User, email: e.target.value })} value={User.email} required />
          <input type="password" name="password" onChange={e=>setUser({...User, password: e.target.value })} value={User.password} required />
          <button type="submit">Add</button>
        </form>
    )
}

server.js

// server

const express = require('express');
const mongoose = require('mongoose');
require('dotenv').config()
var cors = require('cors')
const cookieParser = require('cookie-parser');


// mongodb setup
const dbURI = process.env.DB_URL;
mongoose.connect(dbURI, { useNewUrlParser: true, useUnifiedTopology: true })
  .then(result => console.log('connected to db'))
  .catch(err => console.log(err));

const app= express();
app.use(express.json())
app.use(cors())
app.use(cookieParser());



app.post('/register',(req,res)=>{
const user = new User({
   email : req.user.email,
   displayName : req.user.name,
   password : req.user.password,
   })

user.save()
  .then(usersaved => {
  const accesstoken = jwt.sign({result:usersaved}, process.env.ACCESSTOKEN,{expiresIn: '30d'})
  res.cookie('token',accessToken, { maxAge: 30*24*60*60*1000, httpOnly: true })
  res.json(accessToken)
  })
  .catch(err => {
  console.log('error in saving user')
  res.status(400).send(err)
  })

})

const port = process.env.PORT || 5000
app.listen(port, console.log(`app is running on port ${port}, go to http://localhost:${port}`))