Node.js Overview

Introduction

Node.js is a JavaScript runtime built on Chrome’s V8 engine. It allows developers to build scalable and high-performance applications using an event-driven, non-blocking I/O model.

Installing Node.js

To install Node.js, download it from Node.js Official Website or use a package manager:

# For macOS
brew install node

# For Ubuntu
sudo apt install nodejs npm

Check the installation:

node -v
npm -v

Creating a Simple Node.js Application

Create a file app.js and write the following code:

const http = require('http');
const server = http.createServer((req, res) => {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Hello from Node.js!');
});
server.listen(3000, () => {
    console.log('Server running on port 3000');
});

Run the application:

node app.js

Visit http://localhost:3000 in a browser.

Using npm (Node Package Manager)

npm is used to manage packages in Node.js projects. Initialize a new project:

npm init -y

Install a package (e.g., Express):

npm install express

Creating a Basic Express Server

Install Express:

npm install express

Create server.js:

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

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

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

Run the server:

node server.js

Middleware in Express

Middleware functions handle requests before reaching routes. Example:

app.use((req, res, next) => {
    console.log('Request received');
    next();
});

Working with File System (fs module)

Node.js provides fs module to interact with files. Example:

const fs = require('fs');
fs.writeFileSync('test.txt', 'Hello, Node.js!');
console.log('File created');

Using Environment Variables

Use dotenv to manage environment variables. Install it:

npm install dotenv

Create a .env file:

PORT=3000

Load it in server.js:

require('dotenv').config();
console.log(process.env.PORT);

Conclusion

Node.js is a powerful runtime for building scalable server-side applications. By leveraging npm packages and frameworks like Express, developers can quickly build and deploy web services.

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Happy coding! 🚀