REST API Development in Node.js

A REST API (Representational State Transfer Application Programming Interface) allows applications to communicate using standard HTTP methods and stateless requests.
Node.js is widely used to build REST APIs because of its speed, scalability, and JavaScript-based ecosystem.

1. Core Principles of REST

REST APIs follow these principles:

• Statelessness – Each request is independent

• Client–Server separation

• Uniform interface

• Resource-based URLs

• Standard HTTP methods

2. Common HTTP Methods

3. Setting Up a REST API Project

Install Dependencies

npm init -y
npm install express

Basic Express Server

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

app.use(express.json());

app.listen(3000, () => {
  console.log('API running on port 3000');
});

4. Designing RESTful Routes

Example: User Resource

GET    /users        → Get all users
GET    /users/:id    → Get user by ID
POST   /users        → Create new user
PUT    /users/:id    → Update user
DELETE /users/:id    → Delete user

5. Creating API Endpoints

GET Request

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

POST Request

app.post('/users', (req, res) => {
  users.push(req.body);
  res.status(201).json(req.body);
});

PUT Request

app.put('/users/:id', (req, res) => {
  res.json({ message: 'User updated' });
});

DELETE Request

app.delete('/users/:id', (req, res) => {
  res.json({ message: 'User deleted' });
});

6. Handling JSON Data

app.use(express.json());

✔ Parses incoming JSON requests

7. Error Handling in REST APIs

app.use((err, req, res, next) => {
  res.status(500).json({ error: err.message });
});

8. Status Codes in REST APIs

9. Authentication in REST APIs

Common methods:

• JWT authentication

• API keys

• OAuth

Example:

app.use('/protected', authMiddleware);

10. API Versioning

app.use('/api/v1/users', userRoutes);

✔ Prevents breaking changes

11. Best Practices

• Use meaningful endpoints

• Validate request data

• Use proper HTTP status codes

• Secure APIs with authentication

• Handle errors centrally

• Document APIs clearly

12. Tools for REST API Development

• Postman / Thunder Client – testing

• Swagger / OpenAPI – documentation

• MongoDB / MySQL – database

• JWT – authentication

13. Real-World API Flow

Client Request
     ↓
Router
     ↓
Controller
     ↓
Database
     ↓
JSON Response

14. Summary

• REST APIs enable structured client–server communication

• Node.js and Express simplify API creation

• Proper routing, error handling, and security are crucial

• REST APIs are the backbone of modern applications