Pocket Node-o-Dex

The Emergency Manual

“Don’t lose this, kid. It’s the only thing standing between you and a stack trace.” — Professor Solo

Welcome to the Node-o-Dex. This is your “Hard Hat Required” quick reference for everything we’ve built so far. No fluff, just the specs.

1. Browser vs. Node

One language, two very different job sites.

Feature	Browser (The Sandbox)	Node.js (The Construction Site)
Role	UI Interactivity	Backend Logic & Systems
Global Object	window (The Glass Box)	global (The Foreman)
DOM Access	Yes (document.querySelector)	NO (There is no HTML!)
File System	Restricted (Security)	Full Access (fs)

2. The Ignition Commands

The essential CLI tools to start your engines.

Command	Action
node -v	Checks your installed Node.js version. The “VIN number” of your engine.
node [file]	Executes a JavaScript file (e.g., node app.js). Starts the machinery.
node	Enters the REPL (Read-Eval-Print Loop). Your interactive testing workbench.

3. Site Vitals (Globals)

Variables that are always available on the job site. No import required.

• global: The top-level scope (like window, but for the server).
• __dirname: The absolute path to the directory the current file is in.
• __filename: The absolute path to the current file itself.
• process: The master control object. Environment variables, args, and exit codes.

4. The Supply Chain (Arguments)

Getting materials into the site at runtime.

• process.argv: An array containing command line arguments.
  1. Path to Node executable.
  2. Path to current script.
  3. Your custom arguments (e.g., user).

node app.js --user=Solo
# process.argv[2] === "--user=Solo"

5. The Plumbing (CommonJS)

How we connect the pipes. Node’s legacy module system.

Exporting a Module (The Supply Line):

logger.js

const log = (msg) => console.log(msg);
module.exports = log; // Handing off the tool

Importing a Module (The Intake):

app.js

const logger = require('./logger'); // Grabbing the tool
logger('System Online');

6. Async by Design

Node.js is Non-Blocking. It doesn’t wait for heavy lifting (I/O) to finish before moving to the next task.

• Blocking (Synchronous): The foreman waits for the cement to dry before laying bricks. (Bad for performance).
• Non-Blocking (Asynchronous): The foreman pours cement, moves to lay bricks elsewhere, and comes back when it’s dry.

7. Terminal Shortcuts

Quick reflexes for the command line operator.

• Kill Process: Ctrl + C (The Emergency Stop Button).
• Clear Screen: Ctrl + L or type clear (Sweeping the floor).

8. The Toolbelt (Core Modules)

Standard issue gear. No installation required.

Module	Purpose
fs	File System: Read, write, and manage files.
path	Path Manipulation: Handle file paths safely across OSs (Mac/Windows).
os	Operating System: Check specs (CPU, Memory, Uptime).
http	Networking: Create servers and handle requests.

9. File Operations (FS)

Reading the blueprints.

Reading a File (Async/Promises):

const fs = require('fs').promises; // Modern, Async

// Reading 'manifest.txt'
fs.readFile('./manifest.txt', 'utf-8')
  .then((data) => console.log('Manifest:', data))
  .catch((err) => console.error('Lost the paperwork:', err));

10. Simple HTTP Server

Spinning up a basic web server without any framework scaffolding.

const http = require('http');

// Blueprint for the server
const server = http.createServer((req, res) => {
  if (req.url === '/') {
    res.write('<h1>Job Site Open</h1>');
    res.end();
  }
});

// Open for business on port 3000
server.listen(3000);
console.log('Server running on port 3000...');

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[!TIP] Solo’s Pro-Tip: “Put that ‘Live Server’ EXTENSION away for now and for node. We use node —watch app.js on this site. It restarts the server for us when we save files, but… we will still have to manually refresh the browser for front-end changes.

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Extra Bits & Bytes

📘 Intro to Node.js Study Guide (PDF)