tech

Node.js

JavaScript runtime for server-side development - build scalable network applications with non-blocking I/O

TL;DR

What: JavaScript runtime built on Chrome’s V8 engine for server-side development.

Why: Run JavaScript outside the browser, build fast and scalable network applications.

Quick Start

Install (recommended via nvm):

# Install nvm
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.1/install.sh | bash

# Install latest LTS
nvm install --lts

# Verify installation
node -v  # v24.12.0
npm -v

Alternative installs:

macOS: brew install node

Windows: choco install nodejs or download from nodejs.org

First program:

// hello.js
console.log('Hello, Node.js!');

node hello.js

Create a web server:

// server.js
const http = require('http');

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

server.listen(3000, () => {
  console.log('Server running at http://localhost:3000/');
});

node server.js

Cheatsheet

Command	Description
`node file.js`	Run a JavaScript file
`node -e "code"`	Execute inline code
`node --version`	Show Node.js version
`npm init -y`	Initialize a new project
`npm install pkg`	Install a package
`npm install -g pkg`	Install globally
`npm run script`	Run a package.json script
`npx command`	Run a package without installing

Gotchas

’node’ command not found after install

# Reload shell config
source ~/.bashrc  # or ~/.zshrc
# Or restart terminal

EACCES permission errors with npm

# Use nvm instead of system install
# Or fix npm permissions:
mkdir ~/.npm-global
npm config set prefix '~/.npm-global'
export PATH=~/.npm-global/bin:$PATH

Callback hell

// Use async/await instead
async function getData() {
  const result = await fetch('https://api.example.com');
  return result.json();
}

ES Modules vs CommonJS

// CommonJS (default)
const fs = require('fs');

// ES Modules (use .mjs or set "type": "module" in package.json)
import fs from 'fs';