Node.js Crash Course 💻

Introduction

• No frameworks used (e.g., Express, Fastify, Adonis)
• Focus is on low-level understanding
• Suitable for all skill levels
• We'll set up a server, explore HTTP module, and other core Node.js modules

What is Node.js?

• JavaScript runtime, not a framework, library, or language
• Built with C++ and uses the V8 JavaScript engine (used in Google Chrome)
• Used for server-side, networking applications, APIs, microservices
• JavaScript becomes a full-stack language with Node.js
• Good alternatives: Deno, Bun.js (though Node.js more mature/supported)

Installing Node.js

• Go to nodejs.org, download LTS (recommended) or latest
• Verify installation using node --version and npm --version
• Node.js comes with npm (Node Package Manager)
• REPL available by typing node

Setting Up a Node.js Project

• Create project directory: mkdir nodejs-crash-2024
• Initialize project: npm init
• Create entry point file (e.g., index.js)
• Run file: node index.js
• CommonJS modules: module.exports and require
• ES Modules: export keyword and import syntax

Core Node.js Modules

HTTP Module

• Setting up basic HTTP server: http.createServer()
• Methods: req.method, res.write, res.end, res.setHeader
• Managing status codes: res.statusCode
• Example HTTP server: const http = require('http'); const server = http.createServer((req, res) => { res.setHeader('Content-Type', 'text/html'); res.write('<h1>Hello, World!</h1>'); res.end(); });

Middleware

• Functions handling requests/responses
• Example Logger Middleware: const logger = (req, res, next) => { console.log(`${req.method} ${req.url}`); next(); };

File System (FS) Module

• Reading files: fs.readFile(), fs.readFileSync(), fs.promises.readFile
• Writing files: fs.writeFile(), fs.promises.writeFile
• Appending files: fs.appendFile(), fs.promises.appendFile
• Example for reading a file: const fs = require('fs'); fs.readFile('test.txt', 'utf8', (err, data) => { if (err) throw err; console.log(data); });

Path Module

• Utility for file and directory paths
• Methods: path.basename(), path.dirname(), path.extname(), path.parse(), path.join()
• Example: const path = require('path'); console.log(path.basename('/foo/bar/baz/asdf/test.txt')); // returns 'test.txt'

OS Module

• Provides information about the operating system
• Methods: os.userInfo(), os.totalmem(), os.freemem(), os.cpus()
• Example: const os = require('os'); console.log(os.userInfo()); console.log(os.totalmem()); console.log(os.freemem()); console.log(os.cpus());

URL Module

• Parse URLs and query strings
• Example: const { URL } = require('url'); const myURL = new URL('https://example.org/foo'); console.log(myURL.href); // returns 'https://example.org/foo'

Crypto Module

• Provides cryptographic functionality
• Example (Hashing): const crypto = require('crypto'); const hash = crypto.createHash('sha256'); hash.update('password1234'); console.log(hash.digest('hex'));

Event Emitter

• Create and handle custom events
• Example: const EventEmitter = require('events'); const myEmitter = new EventEmitter(); myEmitter.on('event', () => { console.log('an event occurred!'); }); myEmitter.emit('event');

Conclusion

• Foundation of Node.js covered
• Recommended next steps: Express.js, deeper dive into APIs & middleware
• Resources: Node.js documentation, Express.js crash course, Node.js API masterclass on TraverseMedia.com and Udemy