expressjsHow do I create a backend with Express.js?

Creating a backend with Express.js is a straightforward process. It requires Node.js and npm to be installed beforehand.

Once Node.js and npm are installed, you can create a new project directory and install Express.js with the following commands:

$ mkdir myproject
$ cd myproject
$ npm init -y
$ npm install express

After Express.js is installed, you can create a file named index.js and add the following code to it:

const express = require('express')
const app = express()

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

app.listen(3000, () => console.log('Server running on port 3000'))

The code above will create a server listening on port 3000 and will respond to GET requests with a Hello World! message.

When the code is run, the output should look like this:

$ node index.js
Server running on port 3000

The code consists of the following parts:

• const express = require('express') - imports the Express.js module;
• const app = express() - creates an Express.js application instance;
• app.get('/', (req, res) => { ... }) - defines a route handler for GET requests to the root path;
• res.send('Hello World!') - sends a response with a Hello World! message;
• app.listen(3000, () => console.log('Server running on port 3000')) - starts the server listening on port 3000.

For more information, you can refer to the Express.js documentation.

Edit this code on GitHub