Introduction to ex11 Express.js – Part 1

Express.js is a popular web application framework for Node.js. It is designed to make building web applications and APIs much easier and faster. In this article, we will take a look at some of the basic features of Express.js and how to get started with it.

Setting up Express.js

Before we can start using Express.js, we need to install it. This can be done using npm, which is the package manager for Node.js. Open a terminal and navigate to your project directory, then run the following command:

npm install express

This will install the latest version of Express.js and add it to your project’s dependencies.

Creating a basic Express.js app

Once Express.js is installed, we can start creating our app. Create a new file called app.js in your project directory and open it in your favorite code editor.

First, we need to require Express.js in our app:

const express = require('express');

Then, we can create an instance of the Express application:

const app = express();

Now we have a basic Express app set up. We can start defining routes, handling requests, and much more.

Defining routes in Express.js

Routes in Express.js are HTTP methods and URL paths that map to specific request handlers. For example, we can define a route to handle GET requests to the root URL of our app like this:

app.get('/', (req, res) => {
res.send('Hello, world!');
});

This creates a route that listens for GET requests to the root URL and responds with the text “Hello, world!”.

Starting the Express.js app

After defining our routes, we can start the Express.js app by telling it to listen on a specific port. We can do this by adding the following line to our app.js file:

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

This will start the Express app and make it available on port 3000. You can now access your app by navigating to http://localhost:3000 in your web browser.

That’s it for part 1 of our introduction to Express.js. In part 2, we will explore more advanced features of Express and how to build a more complex web application.