Introduction to Node.js

Node.js is an open-source, cross-platform JavaScript runtime environment that allows developers to run JavaScript on the server side. Built on Chrome's V8 JavaScript engine, Node.js is designed to build scalable, fast, and real-time applications.

Key Features of Node.js:

• Asynchronous & Event-Driven: Node.js operates with a non-blocking, event-driven model, ideal for I/O-heavy applications like chat apps, live data streaming, and APIs.
• Single-Threaded: Uses a single thread to manage multiple requests, making it lightweight and efficient.
• Fast Execution: Node.js is powered by the Google V8 engine, which compiles JavaScript directly to machine code for fast execution.
• Cross-Platform: Works across different platforms, including Windows, Linux, and macOS.

Why Choose Node.js?

• Real-Time Applications: Node.js is great for building real-time apps, such as live chat, notifications, and multiplayer games.
• Full-Stack JavaScript: Use JavaScript for both the client-side and server-side, making it easier to manage and maintain your applications.
• Large Ecosystem: Access to a vast number of libraries and frameworks via npm (Node Package Manager).

Example: Simple Node.js Web Server

Let’s build a simple Node.js server that listens for requests and responds with a "Hello, Node.js!" message.

Steps:

1. Install Node.js: Download and install Node.js from its official website.

2. Create a JavaScript File: Create a file named app.js.

3. Write the Code:

// Import the http module
const http = require('http');

// Create an HTTP server
const server = http.createServer((req, res) => {
  // Set the response HTTP header
  res.writeHead(200, {'Content-Type': 'text/plain'});
  // Send a response
  res.end('Hello, Node.js!');
});

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

Run the Server: In your terminal, navigate to the folder where your app.js file is located and run the following command:

node app.js

Access the Server: Open your browser and go to http://localhost:3000. You should see the message "Hello, Node.js!".

Common Use Cases:

• Web Servers: Build fast and scalable web servers with Node.js.
• Real-Time Apps: Node.js is great for chat applications, notifications, and live updates.
• APIs: Create RESTful APIs that can handle thousands of requests at once.
• Command-Line Tools: Build powerful CLI tools to automate tasks.

This example demonstrates how to create a basic web server with Node.js. It's a great starting point to understand how Node.js handles requests and serves responses.