Node.js Modules

Downloading and Installing Node.js

To install Node.js, follow these steps:

Download Node.js
- Visit the official website: https://nodejs.org/
- Choose the appropriate version:
  - LTS (Long-Term Support): Recommended for most users.
  - Current (Latest Features): For developers who need the newest updates.
Install Node.js
- Run the downloaded installer and follow the setup instructions.
- Ensure you check the box to install npm (Node Package Manager).

Verify Installation

Open a terminal or command prompt and run:

node -v   # Check Node.js version
npm -v    # Check npm version

Global Variables in Node.js

In Node.js, global variables are accessible from anywhere in the application without requiring explicit imports. However, unlike browsers, Node.js does not have a global window object. Instead, it uses the global object.

Common Global Variables in Node.js

global – The root object that holds all global variables.
```
console.log(global); // Displays all global properties
```
_dirname – Returns the directory path of the current module.
```
console.log(__dirname); // Outputs: /Users/example/project
```

__filename – Returns the absolute path of the current file.

console.log(__filename); // Outputs: /Users/example/project/index.js

process – Provides information about the Node.js process.

console.log(process.version); // Outputs Node.js version

console – A built-in debugging tool (similar to console.log in browsers).
```
console.log("Hello, Node.js!"); // Outputs: Hello, Node.js!
```
setTimeout(callback, delay) – Executes a function after a specified delay.
```
setTimeout(() => console.log("Executed after 2 seconds"), 2000);
```
setInterval(callback, interval) – Repeats execution at fixed intervals.
```
setInterval(() => console.log("Runs every 3 seconds"), 3000);
```

require – Used to import modules in CommonJS.

const fs = require("fs"); // Imports file system module

JavaScript is Functional in Nature

JavaScript is often referred to as a functional programming language because it treats functions as first-class citizens. This means: