Backend Project: Login & Registration System

Introduction

In this project, you'll build a login and registration system with Node.js, Express, and MongoDB. This includes user authentication, password hashing, and session management.

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Step 1: Project Setup

Create a new project folder and initialize Node.js:

mkdir login-registration-system
cd login-registration-system
npm init -y
npm install express mongoose bcryptjs jsonwebtoken dotenv

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Step 2: Setting Up Express Server

const express = require('express');
const app = express();
app.use(express.json());

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

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Step 3: Connecting to MongoDB

const mongoose = require('mongoose');
mongoose.connect(process.env.MONGO_URI, {
  useNewUrlParser: true,
  useUnifiedTopology: true,
})
.then(() => console.log('MongoDB connected'))
.catch(err => console.error(err));

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Step 4: Creating User Model

const { Schema, model } = require('mongoose');
const bcrypt = require('bcryptjs');

const userSchema = new Schema({
  username: { type: String, required: true, unique: true },
  email: { type: String, required: true, unique: true },
  password: { type: String, required: true },
});

userSchema.pre('save', async function(next) {
  if(!this.isModified('password')) return next();
  this.password = await bcrypt.hash(this.password, 10);
  next();
});

const User = model('User', userSchema);
module.exports = User;

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Step 5: Registration Route

const express = require('express');
const router = express.Router();
const User = require('./models/User');

router.post('/register', async (req, res) => {
  const { username, email, password } = req.body;
  try {
    const user = new User({ username, email, password });
    await user.save();
    res.status(201).json({ message: 'User registered successfully' });
  } catch(err) {
    res.status(400).json({ error: err.message });
  }
});

module.exports = router;

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Step 6: Login Route with JWT

const jwt = require('jsonwebtoken');
const bcrypt = require('bcryptjs');

router.post('/login', async (req, res) => {
  const { email, password } = req.body;
  const user = await User.findOne({ email });
  if(!user) return res.status(400).json({ error: 'User not found' });

  const isMatch = await bcrypt.compare(password, user.password);
  if(!isMatch) return res.status(400).json({ error: 'Invalid credentials' });

  const token = jwt.sign({ id: user._id }, process.env.JWT_SECRET, { expiresIn: '1h' });
  res.json({ message: 'Login successful', token });
});

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Step 7: Protecting Routes

const authMiddleware = (req, res, next) => {
  const token = req.header('Authorization')?.replace('Bearer ', '');
  if(!token) return res.status(401).json({ error: 'Access denied' });

  try {
    const decoded = jwt.verify(token, process.env.JWT_SECRET);
    req.user = decoded;
    next();
  } catch(err) {
    res.status(400).json({ error: 'Invalid token' });
  }
};

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Step 8: Testing the System

• Use Postman or Insomnia to test registration and login endpoints.
• Check token generation and protected routes.

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Step 9: Best Practices

• Always hash passwords before storing.
• Use environment variables for secrets.
• Implement email verification for added security.
• Validate user input on server side.

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Conclusion

By completing this project, you now have a secure backend login and registration system ready for integration with frontend applications.

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