Node.js Basics

In this episode, we'll dive into the fundamental building blocks of Node.js — the global object, modules, and file system operations.

The Global Object

In the browser, the global object is window. In Node.js, it's global. Some commonly available globals include:

• console — For logging output
• setTimeout / setInterval — For timing operations
• __dirname — The directory path of the current file
• __filename — The full file path of the current file

console.log(__dirname);   // e.g., /Users/you/project
console.log(__filename);  // e.g., /Users/you/project/app.js

Modules and require()

Node.js uses a module system to organize code. Every file is treated as a separate module. You export functionality from one file and import it into another using require():

// utils.js
const greet = (name) => `Hello, ${name}!`;
const add = (a, b) => a + b;

module.exports = { greet, add };

// app.js
const { greet, add } = require('./utils');
console.log(greet('World'));  // Hello, World!
console.log(add(5, 3));      // 8

Built-in Modules

Node.js comes with powerful built-in modules that you don't need to install:

• os — Operating system info
• fs — File system operations
• path — File path utilities
• http — Create HTTP servers
• events — Event-driven programming

Reading and Writing Files

The fs (file system) module lets you interact with files:

const fs = require('fs');

// Reading a file (async)
fs.readFile('./hello.txt', 'utf8', (err, data) => {
    if (err) console.log(err);
    console.log(data);
});

// Writing a file (async)
fs.writeFile('./output.txt', 'Hello from Node!', () => {
    console.log('File written successfully');
});

Always prefer asynchronous methods — they don't block the thread while waiting for I/O to complete.