Explain the concept of RESTful APIs in Express.

RESTful APIs are a popular way of creating web applications that exchange data over the internet in a standardized manner. These APIs follow specific principles such as using resource-based URLs and HTTP methods to perform various operations like creating, reading, updating, and deleting data. ExpressJS is a powerful framework that allows developers to easily create routes, handle requests, and send responses, making it a versatile choice for building APIs that are robust and scalable.

Understanding the concept of RESTful APIs in Express JS:

• REST Architecture: REST, which stands for Representational State Transfer, is an architectural style for designing networked applications.
• Resource-Based: RESTful APIs in ExpressJS are designed around resources, which are identified by unique URLs. These resources represent the entities (e.g., users, products, articles) that the API manipulates.
• HTTP Methods: RESTful APIs use standard HTTP methods to perform CRUD (Create, Read, Update, Delete) operations on resources:
  • GET: Retrieves data from a resource.
  • POST: Creates a new resource.
  • PUT: Updates an existing resource.
  • DELETE: Deletes a resource.
• Statelessness: RESTful APIs are stateless, meaning that each request from a client contains all the information needed to process the request. Servers do not maintain a session state between requests.
• Uniform Interface: RESTful APIs have a uniform interface, which simplifies communication between clients and servers. This interface typically involves the use of standard HTTP methods, resource identifiers (URLs), and representations (e.g., JSON, XML).
• ExpressJS and Routing: In ExpressJS, you define routes to handle incoming requests for specific resources and HTTP methods. Each route specifies a callback function to process the request and send an appropriate response.
• Middleware Integration: ExpressJS middleware can be used to handle tasks such as request validation, authentication, and response formatting, enhancing the functionality and security of RESTful APIs.
• Response Codes: RESTful APIs use standard HTTP status codes to indicate the success or failure of a request. Common status codes include 200 (OK), 201 (Created), 400 (Bad Request), 404 (Not Found), and 500 (Internal Server Error).

Example: Below are the example of RESTful APIs in ExpressJS.

• Install the necessary package in your application using the following command.

npm install express

Example: Below is the basic example of the RESTful API in ExpressJS.

// server.js
const express = require('express');
const app = express();
const PORT = 3000;

// To define the sample data 
let books = [
    {
        id: 1,
        title: 'The Great Gatsby',
        author: 'F. Scott Fitzgerald'
    },
    {
        id: 2,
        title: 'To Kill a Mockingbird',
        author: 'Harper Lee'
    },
];

// Define routes for handling GET requests
app.get('/api/books',
    (req, res) => {
        res.json(books);
    });

app.get('/api/books/:id',
    (req, res) => {
        const id =
            parseInt(req.params.id);
        const book =
            books.find(book => book.id === id);
        if (book) {
            res.json(book);
        } else {
            res.status(404)
                .json({ message: 'Book not found' });
        }
    });

app.listen(PORT,
    () => {
        console.log(`Server is running on port ${PORT}`);
    });

Start your application using the following command.

node server.js

Output: