Create a First App with Node.js 

Creating your first Node.js application is simple and exciting. Follow this guide to build a basic HTTP server that responds with a greeting message.

 

Steps to Create Your First Node.js App

1. Set Up a Project Directory

• Create a directory for your app:

mkdir my-first-node-app
cd my-first-node-app

2. Initialize a Node.js Project

• Initialize a package.json file using npm:

npm init -y

• This creates a default package.json file for managing project dependencies.

3. Create the Application File

• Create a JavaScript file for your app:

touch app.js

4. Write the Code

• Open app.js in a code editor and add the following code:

const http = require('http');

// Create server
const server = http.createServer((req, res) => {
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('Hello, Node.js!');
});

// Listen on port 3000
server.listen(3000, () => {
  console.log('Server is running at http://localhost:3000');
});

5. Run the Application

• Start the server:

node app.js

• Open your browser and navigate to http://localhost:3000.

6. Output

• Browser will display:

Hello, Node.js!

• Terminal will show:

Server is running at http://localhost:3000

 

Explanation of Code

1. http Module

• Built-in module to create an HTTP server.

2. createServer Method

• Handles incoming requests and sends responses.

3. Response Methods

• res.writeHead: Sets the HTTP status and headers.
• res.end: Sends the response body and ends the request.

4. listen Method

• Specifies the port number (3000 in this case) on which the server will listen.

 

Summary

In just a few steps, you’ve built your first Node.js application: a basic HTTP server. This foundation is a stepping stone to creating more complex applications, such as APIs, real-time services, and web apps. Happy coding!