Express.js, often referred to simply as Express, is a popular and powerful web application framework for Node.js. It provides a robust set of features for building web and mobile applications. In this comprehensive guide, we will dive deep into creating RESTful APIs using Express.js, covering everything from the basics to advanced topics.
Introduction to RESTful APIs
RESTful APIs (Representational State Transfer) are a set of architectural principles for designing networked applications. They use HTTP methods to perform CRUD (Create, Read, Update, Delete) operations on resources, which are represented as URLs. RESTful APIs have become the standard for building web services due to their simplicity and scalability.
Express.js is a minimal and flexible Node.js web application framework that provides a robust set of features for web and mobile applications. It is often used to build RESTful APIs because of its simplicity and ability to handle HTTP requests and responses efficiently.
In this guide, we will explore how to create RESTful APIs using Express.js. We'll start from the basics and gradually move into more advanced topics, ensuring you have a solid understanding of building RESTful APIs with Express.js.
Getting Started with Express.js
Installing Express.js
Before you can start building RESTful APIs with Express.js, you need to set up your development environment. Ensure that you have Node.js installed on your system; you can download it from the official Node.js website.
To create a new Express.js application, you'll also need to install the Express.js package. You can do this using npm, the Node.js package manager. Open your terminal and run the following command:
npm install express --save
This command installs the Express.js package and adds it as a dependency to your project. The --save flag ensures that it's added to your project's package.json file.
Creating Your First Express.js Application
Once Express.js is installed, you can create your first Express application. Here's a simple "Hello, Express!" example:
const express = require('express');
const app = express();
const port = 3000;
app.get('/', (req, res) => {
res.send('Hello, Express!');
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example:
We import the
expressmodule and create an Express application usingexpress().We define a route for the root URL (
'/') usingapp.get(). When a GET request is made to the root URL, the server responds with "Hello, Express!".We start the server and make it listen on port 3000 using
app.listen().
You can run this application by saving it to a file (e.g., app.js) and executing it using Node.js:
node app.js
Now, if you open your web browser and navigate to http://localhost:3000, you should see the "Hello, Express!" message.
Congratulations! You've created your first Express.js application. Next, let's explore routing and handling requests.
Routing and Handling Requests
Defining Routes
In Express.js, routing refers to determining how an application responds to a client request for a specific URL. You define routes using HTTP methods (such as GET, POST, PUT, DELETE) and associate them with functions that handle requests and send responses.
Here's an example of defining multiple routes in an Express application:
const express = require('express');
const app = express();
const port = 3000;
// Define a GET route for the root URL
app.get('/', (req, res) => {
res.send('Hello, Express!');
});
// Define a GET route for /about
app.get('/about', (req, res) => {
res.send('This is the about page.');
});
// Define a POST route for /submit
app.post('/submit', (req, res) => {
res.send('Form submitted successfully.');
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example:
We define a GET route for the root URL (
'/') and respond with "Hello, Express!" when accessed.We define a GET route for
/aboutand respond with "This is the about page." when accessed.We define a POST route for
/submitand respond with "Form submitted successfully." when accessed with a POST request.
Handling HTTP Methods
HTTP methods (or HTTP request methods) are used to indicate the desired action to be performed on a resource. Express.js provides methods for handling different HTTP methods, such as get(), post(), put(), and delete(). Here's how you can use them:
const express = require('express');
const app = express();
const port = 3000;
// Handling a GET request
app.get('/', (req, res) => {
res.send('GET request received.');
});
// Handling a POST request
app.post('/', (req, res) => {
res.send('POST
request received.');
});
// Handling a PUT request
app.put('/', (req, res) => {
res.send('PUT request received.');
});
// Handling a DELETE request
app.delete('/', (req, res) => {
res.send('DELETE request received.');
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example, we've defined routes for each of the four HTTP methods (GET, POST, PUT, DELETE). When you make requests to the root URL ('/') using these methods, the server will respond with the corresponding message.
This demonstrates the basic routing capabilities of Express.js. You can define more complex routes and use parameters to capture dynamic parts of URLs, which is especially useful for building RESTful APIs.
Middleware
Middleware functions in Express.js are functions that have access to the request and response objects. They can perform tasks such as processing data, authentication, logging, and more. Middleware functions can be used to customize the behavior of your application's routes.
Built-in Middleware
Express.js provides several built-in middleware functions that can be used to handle common tasks. Here are some examples:
express.json(): This middleware parses incoming JSON data, making it accessible in thereq.bodyobject. It's commonly used for handling JSON requests.
const express = require('express');
const app = express();
const port = 3000;
app.use(express.json());
app.post('/json', (req, res) => {
console.log(req.body); // Access JSON data from the request body
res.send('JSON data received.');
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
express.urlencoded(): This middleware parses incoming URL-encoded data, making it accessible in thereq.bodyobject. It's commonly used for handling form submissions.
const express = require('express');
const app = express();
const port = 3000;
app.use(express.urlencoded({ extended: true }));
app.post('/form', (req, res) => {
console.log(req.body); // Access URL-encoded data from the request body
res.send('Form data received.');
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
express.static(): This middleware serves static files, such as HTML, CSS, and JavaScript, from a specified directory. It's useful for serving assets like images, stylesheets, and client-side scripts.
const express = require('express');
const app = express();
const port = 3000;
// Serve static files from the "public" directory
app.use(express.static('public'));
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
Custom Middleware
You can also create custom middleware functions to perform specific tasks. Middleware functions are typically defined using the app.use() method, and they are executed in the order they are defined. Here's an example of a custom middleware function that logs requests:
const express = require('express');
const app = express();
const port = 3000;
// Custom middleware for logging requests
app.use((req, res, next) => {
console.log(`Received a ${req.method} request to ${req.url}`);
next(); // Call next() to pass control to the next middleware
});
app.get('/', (req, res) => {
res.send('Hello, Express!');
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example, the custom middleware logs information about each incoming request, including the HTTP method and URL. The next() function is called to pass control to the next middleware in the stack.
Middleware allows you to modularize and customize the behavior of your Express.js application. It's a powerful feature that enables you to add functionality to your routes without cluttering your route handlers.
Request and Response Objects
In Express.js, each route handler receives two important objects: the request (often abbreviated as req) and the response (often abbreviated as res). These objects provide information about the incoming request and allow you to send a response back to the client.
Working with Request Data
The request object (req) contains information about the incoming HTTP request, including headers, parameters, query strings, and request body data. Here are some common properties and methods of the req object:
req.params: An object containing route parameters extracted from the URL. For example, if you define a route like/users/:id, you can access theidparameter usingreq.params.id.
app.get('/users/:id', (req, res) => {
const userId = req.params.id;
res.send(`User ID: ${userId}`);
});
req.query: An object containing query string parameters from the URL. For example, if the URL is/search?q=express, you can access theqparameter usingreq.query.q.
app.get('/search', (req, res) => {
const query = req.query.q;
res.send(`Search query: ${query}`);
});
req.body: Data from the request body, available when using middleware likeexpress.json()andexpress.urlencoded(). For example, for a JSON request, you can access data in the request body usingreq.body.
app.use(express.json());
app.post('/api/data', (req, res) => {
const data = req.body;
res.json(data);
});
req.headers: An object containing the HTTP headers of the request. You can access specific headers using property names.
app.get('/user-agent', (req, res) => {
const userAgent = req.headers['user-agent'];
res.send(`User-Agent: ${userAgent}`);
});
Sending Responses
The response object (res) is used to send a response back to the client. It provides methods to set HTTP status codes, send data, and set headers. Here are some common methods of the res object:
res.send(data): Sends data as a response. Thedatacan be a string, an object, an array, or even HTML markup. Express.js automatically sets theContent-Typeheader based on the data.
app.get('/hello', (req, res) => {
res.send('Hello, Express!');
});
res.json(data): Sends a JSON response. This method sets theContent-Typeheader toapplication/jsonand converts thedataparameter to a JSON string.
app.get('/api/data', (req, res) => {
const data = { name: 'John', age: 30 };
res.json(data);
});
res.status(code): Sets the HTTP status code of the response. For example, to send a "Not Found" response with a
status code of 404:
app.get('/not-found', (req, res) => {
res.status(404).send('Not Found');
});
res.setHeader(name, value): Sets an HTTP response header. For example, to set theCache-Controlheader:
app.get('/cache-control', (req, res) => {
res.setHeader('Cache-Control', 'max-age=3600');
res.send('This response is cacheable for 1 hour.');
});
res.redirect(url): Redirects the client to a different URL. For example, to redirect from/oldto/new:
app.get('/old', (req, res) => {
res.redirect('/new');
});
Understanding how to work with request and response objects is crucial for building RESTful APIs, as it allows you to handle client requests and send appropriate responses.
CRUD Operations
RESTful APIs are commonly used for performing CRUD (Create, Read, Update, Delete) operations on resources. In this section, we'll explore how to implement these operations using Express.js.
Creating Records
To create records (or resources) using an Express.js API, you typically handle POST requests. Clients send data in the request body, which you can access using req.body. Here's an example of creating a new user:
const express = require('express');
const app = express();
const port = 3000;
app.use(express.json());
const users = [];
// Create a new user
app.post('/users', (req, res) => {
const newUser = req.body;
users.push(newUser);
res.status(201).json(newUser); // Respond with the created user and a 201 status code
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example:
We define an array called
usersto store user objects.The POST request handler (
/users) extracts the new user data fromreq.bodyand adds it to theusersarray.We respond with the newly created user object and set the HTTP status code to 201 (Created).
Reading Records
To read records, you typically handle GET requests. Clients can request specific resources or retrieve a list of resources. Here's an example of reading user data:
const express = require('express');
const app = express();
const port = 3000;
const users = [
{ id: 1, name: 'Alice' },
{ id: 2, name: 'Bob' },
];
// Get a list of all users
app.get('/users', (req, res) => {
res.json(users);
});
// Get a specific user by ID
app.get('/users/:id', (req, res) => {
const userId = parseInt(req.params.id);
const user = users.find((u) => u.id === userId);
if (!user) {
return res.status(404).json({ message: 'User not found' });
}
res.json(user);
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example:
We have an array called
userscontaining user objects.The
/usersroute handler responds with the list of all users when a GET request is made to that endpoint.The
/users/:idroute handler retrieves a specific user by ID and responds with the user object. If the user is not found, it responds with a 404 status code and a message.
Updating Records
To update records, you typically handle PUT or PATCH requests. Clients send updated data in the request body, and you use that data to modify the resource. Here's an example of updating a user's information:
const express = require('express');
const app = express();
const port = 3000;
app.use(express.json());
let users = [
{ id: 1, name: 'Alice' },
{ id: 2, name: 'Bob' },
];
// Update a user's information by ID
app.put('/users/:id', (req, res) => {
const userId = parseInt(req.params.id);
const updatedUser = req.body;
const userIndex = users.findIndex((u) => u.id === userId);
if (userIndex === -1) {
return res.status(404).json({ message: 'User not found' });
}
users[userIndex] = { ...users[userIndex], ...updatedUser };
res.json(users[userIndex]);
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example:
We define a
usersarray with user objects.The
/users/:idroute handler extracts the user's ID from the URL parameter and the updated data from the request body.It finds the user in the
usersarray, updates the user's information, and responds with the updated user object.
Deleting Records
To delete records, you typically handle DELETE requests. Clients request the deletion of a specific resource, and you remove that resource from your data store. Here's an example of deleting a user:
const express = require('express');
const app = express();
const port = 3000;
let users = [
{ id: 1, name: 'Alice' },
{ id: 2, name: 'Bob' },
];
// Delete a user by ID
app.delete('/users/:id', (req, res) => {
const userId = parseInt(req.params.id);
const userIndex = users.findIndex((u) => u.id === userId);
if (userIndex === -1) {
return res.status(404).json({ message: 'User not found' });
}
const deletedUser = users.splice(userIndex, 1)[0];
res.json(deletedUser);
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example:
We have a
usersarray containing user objects.The
/users/:idroute handler extracts the user's ID from the URL parameter.It finds the user in the
usersarray, deletes the user, and responds with the deleted user object.
These examples demonstrate how to perform CRUD operations using Express.js. However, building a complete RESTful API involves more than just handling routes for CRUD operations. You'll need to implement validation, error handling, authentication, and authorization, which we'll explore in the following sections.
Validation and Error Handling
Building a robust RESTful API involves validating incoming data and handling errors gracefully. Express.js provides mechanisms for data validation and error handling to ensure the reliability and security of your API.
Data Validation
Data validation is crucial to ensure that incoming data meets your API's requirements and is safe to use. You can perform data validation in middleware functions or route handlers using libraries like express-validator.
Here's an example of using
express-validator to validate a POST request's data before creating a new user:
const express = require('express');
const { body, validationResult } = require('express-validator');
const app = express();
const port = 3000;
app.use(express.json());
let users = [];
// Data validation middleware
const validateUserData = [
body('name').isLength({ min: 1 }).withMessage('Name is required'),
body('email').isEmail().withMessage('Invalid email address'),
];
// Create a new user
app.post(
'/users',
validateUserData, // Apply validation middleware
(req, res) => {
const errors = validationResult(req);
if (!errors.isEmpty()) {
return res.status(400).json({ errors: errors.array() });
}
const newUser = req.body;
users.push(newUser);
res.status(201).json(newUser);
}
);
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example:
We import the
bodyandvalidationResultfunctions fromexpress-validator.We define a middleware function called
validateUserDatathat checks if thenameis not empty and if theemailis a valid email address.The
validateUserDatamiddleware is applied to the POST route for creating users.Inside the route handler, we use
validationResult(req)to check for validation errors. If there are errors, we respond with a 400 status code and the list of errors.
Error Handling
Error handling is essential to handle unexpected issues that may arise during API operations. Express.js provides ways to catch and handle errors using middleware functions.
Here's an example of a global error handler that logs errors and sends a generic error response to clients:
const express = require('express');
const app = express();
const port = 3000;
app.use(express.json());
// Simulate an error
app.get('/simulate-error', (req, res, next) => {
const error = new Error('Simulated error');
error.status = 500; // Set the status code
next(error); // Pass the error to the next middleware
});
// Global error handler
app.use((err, req, res, next) => {
console.error(err); // Log the error
const statusCode = err.status || 500;
res.status(statusCode).json({ message: 'An error occurred' });
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example:
We have a route (
/simulate-error) that simulates an error by throwing an error with a 500 status code.We define a global error handler middleware using
app.use(). This middleware catches errors thrown in route handlers or other middleware.Inside the error handler, we log the error and respond with a generic error message and an appropriate status code.
Custom error handling allows you to centralize error management and provide consistent error responses to clients.
Authentication and Authorization
Authentication and authorization are crucial aspects of building secure RESTful APIs. Authentication verifies the identity of users, while authorization determines what actions they are allowed to perform.
Authentication
Express.js does not provide built-in authentication mechanisms, but you can integrate authentication libraries or services to secure your API. Common authentication methods for RESTful APIs include JSON Web Tokens (JWT), OAuth, and Basic Authentication.
Here's an example of implementing JWT-based authentication using the jsonwebtoken library:
const express = require('express');
const jwt = require('jsonwebtoken');
const app = express();
const port = 3000;
app.use(express.json());
const secretKey = 'your-secret-key'; // Replace with a strong, secret key
// Simulated user data (for demonstration purposes)
const users = [
{ id: 1, username: 'user1', password: 'password1' },
{ id: 2, username: 'user2', password: 'password2' },
];
// Generate a JWT token for authentication
function generateToken(user) {
return jwt.sign({ userId: user.id }, secretKey, { expiresIn: '1h' });
}
// Authenticate user and issue a JWT token
app.post('/login', (req, res) => {
const { username, password } = req.body;
const user = users.find((u) => u.username === username && u.password === password);
if (!user) {
return res.status(401).json({ message: 'Invalid credentials' });
}
const token = generateToken(user);
res.json({ token });
});
// Protected route that requires authentication
app.get('/protected', (req, res) => {
// The user's information is available in req.user (set by middleware)
res.json({ message: 'Protected resource accessed', user: req.user });
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example:
We use the
jsonwebtokenlibrary to generate and verify JWT tokens.The
/loginroute handles user authentication by checking the provided username and password against the simulated user data.If authentication is successful, a JWT token is generated and sent back to the client.
The
/protectedroute is a protected resource that requires a valid JWT token. We use middleware to verify the token and setreq.userwith the user's information.
Please note that this is a simplified example, and in a real-world scenario, you should use a more secure method for storing and comparing passwords (e.g., hashing).
Authorization
Authorization controls what actions users are allowed to perform on resources. You can implement authorization logic in your route handlers or use middleware to check user permissions.
Here's an example of implementing basic authorization using middleware:
const express = require('express');
const jwt = require('jsonwebtoken');
const app = express();
const port = 3000;
app.use(express.json());
const secretKey = 'your-secret-key';
// Middleware to authenticate and authorize users
function authenticateAndAuthorize(req, res, next) {
// Check if the request has a valid JWT token
const token = req.headers.authorization;
if (!token) {
return res.status(401).json({ message: 'Authentication required' });
}
try {
const decodedToken = jwt.verify(token, secretKey);
req.user = decodedToken; // Set the user information in the request
next(); // Continue to the next middleware or route handler
} catch (error) {
return res.status(403).json({ message: 'Unauthorized' });
}
}
// Protected route that requires authentication and authorization
app.get('/profile', authenticateAndAuthorize, (req, res) => {
// Check user permissions (for demonstration purposes)
if (req.user.role !== 'admin') {
return res.status(403).json({ message: 'Access denied' });
}
res.json({ message: 'Access granted', user: req.user });
});
app.listen(port, () => {
console.log(`Server is listening on port ${port}`);
});
In this example:
- We create a custom middleware function
authenticateAndAuthorize
to handle both authentication and authorization.
The middleware checks for the presence of a valid JWT token in the request headers and verifies it using
jsonwebtoken.If authentication is successful, the user information is set in
req.user, and the request is passed to the next middleware or route handler.In the
/profileroute handler, we demonstrate an authorization check by verifying the user's role. Users with the role of 'admin' are granted access.
Authentication and authorization are critical for securing your RESTful API. Depending on your application's requirements, you may need to implement more advanced authentication and authorization mechanisms.
Testing Express.js Applications
Testing is a crucial part of software development, ensuring the correctness and reliability of your application. In this section, we'll explore how to test Express.js applications, including unit testing and integration testing.
Unit Testing
Unit testing involves testing individual units or components of your application in isolation. In the context of Express.js, you can unit test route handlers, middleware functions, and other parts of your codebase.
To perform unit testing in Node.js, you can use testing libraries like Mocha and assertion libraries like Chai. Here's a basic example of unit testing an Express route handler:
const assert = require('chai').assert;
const request = require('supertest');
const express = require('express');
const app = express();
app.get('/hello', (req, res) => {
res.send('Hello, Express!');
});
describe('Express Route Tests', () => {
it('should return "Hello, Express!"', (done) => {
request(app)
.get('/hello')
.expect(200)
.end((err, res) => {
if (err) return done(err);
assert.equal(res.text, 'Hello, Express!');
done();
});
});
});
In this example:
We use the
Mochatesting framework to define a test suite and test case.We use the
supertestlibrary to make HTTP requests to the Express application.In the test case, we send a GET request to the
/helloendpoint and assert that the response body is "Hello, Express!".
This is a simple unit test, but you can write more extensive tests to cover various scenarios and edge cases in your application.
Integration Testing
Integration testing involves testing the interactions between different components or modules of your application. In the context of Express.js, integration tests can be used to test the behavior of multiple routes, middleware functions, and database interactions.
Here's an example of an integration test that tests the interaction between multiple routes:
const assert = require('chai').assert;
const request = require('supertest');
const express = require('express');
const app = express();
app.get('/hello', (req, res) => {
res.send('Hello, Express!');
});
app.get('/about', (req, res) => {
res.send('This is the about page.');
});
describe('Express Integration Tests', () => {
it('should return "Hello, Express!" from /hello', (done) => {
request(app)
.get('/hello')
.expect(200)
.end((err, res) => {
if (err) return done(err);
assert.equal(res.text, 'Hello, Express!');
done();
});
});
it('should return "This is the about page." from /about', (done) => {
request(app)
.get('/about')
.expect(200)
.end((err, res) => {
if (err) return done(err);
assert.equal(res.text, 'This is the about page.');
done();
});
});
});
In this example:
We define an Express application with two routes:
/helloand/about.We write integration tests for both routes using
Mochaandsupertest. Each test makes a request to a specific route and asserts the expected response.
Integration tests can also include database interactions, authentication, and other complex scenarios to ensure that your Express.js application functions correctly as a whole.
Advanced Topics
In addition to the fundamental concepts covered so far, building RESTful APIs with Express.js involves many advanced topics. Here are a few advanced topics you may encounter:
Pagination
Pagination is a technique used to limit the number of results returned from an API endpoint and provide navigation options for accessing additional results. You can implement pagination in your Express.js API by accepting query parameters for page and limit.
app.get('/users', (req, res) => {
const page = parseInt(req.query.page) || 1;
const limit = parseInt(req.query.limit) || 10;
const startIndex = (page - 1) * limit;
const endIndex = page * limit;
const paginatedUsers = users.slice(startIndex, endIndex);
res.json({ users: paginatedUsers });
});
In this example, the /users route accepts query parameters for page and limit to control the pagination of user data.
File Uploads
If your API needs to handle file uploads, you can use middleware like multer to handle file uploads in Express.js. multer allows you to process and store uploaded files.
const multer = require('multer');
const storage = multer.diskStorage({
destination: (req, file, cb) => {
cb(null, 'uploads/');
},
filename: (req, file, cb) => {
cb(null, file.originalname);
},
});
const upload = multer({ storage });
app.post('/upload', upload.single('file'), (req, res) => {
const uploadedFile = req.file;
res.json({ message: 'File uploaded', file: uploadedFile });
});
In this example, we use multer to handle file uploads, and the uploaded file is available as req.file in the route handler.
Caching
Caching can improve the performance of your API by storing and reusing responses for specific requests. You can implement caching using middleware or cache libraries like node-cache or Redis.
const NodeCache = require('node-cache');
const cache = new NodeCache({ stdTTL: 60 }); // Cache for 60 seconds
app.get('/data', (req, res) => {
const cachedData = cache.get('data');
if (cachedData) {
return res.json({ source: 'cache', data: cachedData });
}
// If data is not cached, fetch and cache it
const data = fetchDataFromDatabase();
cache.set('data', data);
res.json({ source: 'database', data: data });
});
In this example, we use the node-cache library to cache data fetched from a database for a specified duration.
WebSockets
While Express.js is primarily designed for handling HTTP requests, you can integrate WebSockets into your Express application using libraries like socket.io. WebSockets enable real-time communication between clients and the
server.
const express = require('express');
const http = require('http');
const socketIo = require('socket.io');
const app = express();
const server = http.createServer(app);
const io = socketIo(server);
io.on('connection', (socket) => {
console.log('A user connected');
socket.on('chat message', (message) => {
io.emit('chat message', message);
});
socket.on('disconnect', () => {
console.log('A user disconnected');
});
});
app.get('/', (req, res) => {
res.sendFile(__dirname + '/index.html');
});
server.listen(3000, () => {
console.log('Server is listening on port 3000');
});
In this example, we create a basic chat application that uses WebSockets for real-time communication between clients and the server.
Conclusion
Building RESTful APIs with Express.js is a powerful and versatile approach for creating web services and applications. In this comprehensive guide, we've covered the fundamental concepts of building RESTful APIs with Express.js, including routing, middleware, request and response objects, CRUD operations, validation, error handling, authentication, authorization, and testing.
Express.js provides a robust foundation for creating APIs, and its flexibility allows you to tailor your API to meet the specific requirements of your project. Whether you're building a simple API or a complex web application, Express.js is a popular choice among Node.js developers for its ease of use and extensive ecosystem of middleware and libraries.
As you continue to work with Express.js, you'll encounter more advanced topics and challenges, such as pagination, file uploads, caching, WebSockets, and more. Expanding your knowledge of Express.js and exploring these advanced topics will enable you to build high-performance, feature-rich APIs that meet the needs of your users and clients.