Node.js

 1. What is Node.js?

Node.js is an open-source, server-side JavaScript runtime environment that allows you to execute JavaScript code outside of a web browser. It uses the V8 JavaScript engine from Google Chrome to run JavaScript code on the server-side, enabling you to build scalable and high-performance applications.

2. Installation To get started with Node.js, you'll need to install it on your machine. Visit the official Node.js website (https://nodejs.org) and download the appropriate installer for your operating system. Once installed, you can access Node.js from your terminal or command prompt.

3. Creating a Simple Server Let's create a simple HTTP server using Node.js. Open your text editor and create a new file called server.js.

javascript
const http = require('http');

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

const port = 3000;
server.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`);
});

4. Running the Server Save the server.js file, open your terminal or command prompt, navigate to the directory where the file is saved, and run the following command:

node server.js

This will start your server, and you should see the message "Server is running on http://localhost:3000". Now open your web browser and visit http://localhost:3000, and you should see "Hello, World!" displayed on the page.

5. NPM (Node Package Manager) NPM is the package manager for Node.js, allowing you to install and manage external libraries (packages) easily. It comes bundled with Node.js. You can initialize a new Node.js project and create a package.json file by running the following command in your project directory:

csharp
npm init

6. Installing External Packages You can install packages using NPM by running:

go
npm install package-name

For example, to install the express package, you would run:

npm install express

7. Creating an Express App Express is a popular web framework for Node.js that simplifies building web applications. First, install Express using NPM:

npm install express

Then, create a new file called app.js:

javascript
const express = require('express');
const app = express();
const port = 3000;

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

app.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`);
});

8. Running the Express App Save the app.js file, open your terminal or command prompt, navigate to the directory where the file is saved, and run the following command:

node app.js

Visit http://localhost:3000, and you should see "Hello, Express!" displayed on the page.

This is just the beginning of what you can do with Node.js. There's a vast ecosystem of libraries and frameworks available to help you build web applications, APIs, command-line tools, and more. As you progress, you'll likely need to learn about asynchronous programming, working with databases, and other advanced concepts.