⚙️ Backend
🛠️ Backend Frameworks
Express.js

Express.js (opens in a new tab)

Express.js is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications.

Core Concepts

Middleware 🛠️

  • Definition: Functions that have access to the request and response objects
  • Chain Processing: Execute in order of definition
  • Common Use Cases:
    • Authentication
    • Body parsing
    • CORS handling
    • Error handling
    • Logging

Routing 🗺️

app.get('/users', (req, res) => {
  res.json(users);
});
 
app.post('/users', (req, res) => {
  // Create new user
});

Request Handling 📦

  • Query parameters
  • Route parameters
  • Request body
  • Headers
  • Cookies

Database Integration 🗄️

MongoDB (opens in a new tab) with Mongoose (opens in a new tab)

const mongoose = require('mongoose');
 
const userSchema = new mongoose.Schema({
  name: String,
  email: String
});
 
const User = mongoose.model('User', userSchema);

SQL with Sequelize (opens in a new tab)

const { Sequelize, Model, DataTypes } = require('sequelize');
const sequelize = new Sequelize('database', 'username', 'password');
 
class User extends Model {}
User.init({
  name: DataTypes.STRING,
  email: DataTypes.STRING
}, { sequelize });

Error Handling ⚠️

app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).send('Something broke!');
});

Authentication 🔐

JWT Implementation

const jwt = require('jsonwebtoken');
 
app.post('/login', (req, res) => {
  // Verify user credentials
  const token = jwt.sign({ userId: user.id }, 'secret_key');
  res.json({ token });
});

Best Practices

Project Structure

project/
  ├── controllers/
  ├── models/
  ├── routes/
  ├── middleware/
  ├── config/
  └── app.js

Security Measures

  • Use Helmet.js for security headers
  • Implement rate limiting
  • Validate input data
  • Use CORS properly
  • Set secure cookies

Performance Optimization

  • Use compression middleware
  • Implement caching
  • Optimize database queries
  • Use async/await properly

Deployment

Production Considerations

  • Environment variables
  • Process managers (PM2)
  • Load balancing
  • Monitoring and logging
  • SSL/TLS configuration

Additional Resources

🛠️ Backend FrameworksNestJS