Express.js is a powerful web application framework for Node.js that provides a simple and efficient way to build web applications. It is widely used and has gained popularity due to its minimalist approach and robust set of features.
Why Choose Express.js?
Express.js is a great choice for beginners because of its simplicity. Its minimalistic design allows developers to quickly understand and work with the framework. Additionally, Express.js is highly extensible, which means you can easily add more functionalities as your project grows.
Another advantage of Express.js is its strong community support. There is a vast amount of resources available online, including tutorials, documentation, and forums, where you can find help and guidance throughout your journey with Express.js.
Setting Up Express.js
To get started with Express.js, you need to have Node.js installed on your computer. Node.js is a JavaScript runtime that allows you to run JavaScript code outside of a browser.
Once you have Node.js installed, you can create a new directory for your project and navigate to it using the command line interface. Then, run the following command to initialize a new Node.js project:
npm init
This command will create a `package.json` file, which will keep track of your project’s dependencies and other essential information.
To install Express.js, use the following command:
npm install express
This will download and install the Express.js library into your project directory.
Creating Your First Express.js Application
Now that you have Express.js installed, it’s time to create your first application.
Create a new file called `app.js` in your project directory, and open it using a text editor.
In `app.js`, start by adding the following code:
const express = require('express');
const app = express();
This code imports the Express.js library and creates a new instance of the Express application.
Next, add the following code to define a basic route:
app.get('/', (req, res) => {
res.send('Hello, World!');
});
This code creates a route that responds with the text ‘Hello, World!’ when the root URL is visited.
Finally, add the following code to start the application:
app.listen(3000, () => {
console.log('Server started on port 3000');
});
This code tells Express.js to start listening on port 3000. You can change the port number if needed.
Save the `app.js` file, and in the command line interface, run the following command:
node app.js
Now, if you visit `http://localhost:3000` in your browser, you should see the message “Hello, World!” displayed.
Adding Routes and Middleware
Express.js allows you to define various routes and use middleware to handle them. Routes represent different URLs that users can access, and middleware provides additional functionality to your application.
To add a new route, you can use the `app.get()` or `app.post()` function, depending on the HTTP method you want to handle.
For example, to create a route for the URL `/about`, you can add the following code:
app.get('/about', (req, res) => {
res.send('This is the about page.');
});
Visiting `http://localhost:3000/about` will display the message “This is the about page.”
You can also use middleware to perform actions before a route is handled. Middleware functions can be added using the `app.use()` function.
For example, to create a logger middleware that logs the URL of each incoming request, you can add the following code:
app.use((req, res, next) => {
console.log(`Requested URL: ${req.url}`);
next();
});
The `next()` function is used to pass control to the next middleware or route handler.
Conclusion
Express.js is an excellent choice for beginners looking to build web applications using Node.js. Its simplicity, extensive community support, and powerful features make it an ideal framework for development.
In this beginner’s guide, you learned how to set up Express.js, create your first application, and add routes and middleware to handle different URLs.
Now that you have a basic understanding, you can explore more of Express.js’s features and start building more complex and powerful web applications.
