Express.js Fundamentals

Express.js is a popular framework for building web applications and APIs with Node.js. It provides a fast, unopinionated, and minimalist web application framework that allows you to easily handle routes, requests, and responses.

To get started with Express.js, you need to install it using npm or yarn:

1// npm
2npm install express
3
4// yarn
5yarn add express

Once installed, you can create an Express.js server by requiring the express module and calling express() to create an instance of the app. Here's a basic example:

1const express = require('express');
2const app = express();
3
4app.get('/', (req, res) => {
5  res.send('Hello, world!');
6});
7
8app.listen(3000, () => {
9  console.log('Server is running on port 3000');
10});

In this example, we create a server that listens on port 3000 and handles GET requests to the root path ('/'). When a request is made to the root path, it sends the response 'Hello, world!'.

Express.js provides a robust set of features for building web applications, including routing, middleware, template engines, and more. It is widely used in the industry and has a large and active community.

With Express.js, you can easily build powerful server-side applications and APIs that integrate with other frontend frameworks like React. It is a key component of the MERN stack (MongoDB, Express.js, React, Node.js) for full-stack JavaScript development.

Keep in mind that this is just a basic introduction to Express.js. There are many more concepts and features to explore, such as routing, error handling, authentication, and database integration.

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// replace with relevant Express.js code

const express = require('express');

const app = express();

​

app.get('/', (req, res) => {

  res.send('Hello, world!');

});

​

app.listen(3000, () => {

  console.log('Server is running on port 3000');

})