Node.js Installation & Setup

What is NPM?

NPM (Node Package Manager) is the default package manager for Node.js and the world's largest software registry with over 2 million packages.

What Can You Do with NPM?

npm install express
npm install -g nodemon
npm install --save-dev jest
npm run start
npm update
npm uninstall express

Why Do You Need NPM?

• Code Reusability - avoid rewriting common tools
• Version Management - lock exact/compatible package versions
• Dependency Management - auto handles transitive dependencies
• Script Running - start/test/build commands from one place
• Sharing Code - publish reusable packages

Pre-installation Checklist

Check if Node.js is Already Installed

node --version
npm --version
# If command not found, continue installation

Windows Installation

Method 1: Official Installer (Recommended)

1. Visit nodejs.org and download LTS `.msi`.
2. Run installer, accept license, keep default path `C:\Program Files\nodejs\`.
3. Ensure options enabled: Node runtime, npm, Add to PATH.
4. Install and restart if prompted.

Method 2: Chocolatey

# Run as Administrator
Set-ExecutionPolicy Bypass -Scope Process -Force
[System.Net.ServicePointManager]::SecurityProtocol = [System.Net.ServicePointManager]::SecurityProtocol -bor 3072
iex ((New-Object System.Net.WebClient).DownloadString('https://community.chocolatey.org/install.ps1'))
choco install nodejs
choco install nodejs-lts

Method 3: Winget

winget search nodejs
winget install OpenJS.NodeJS.LTS
winget install OpenJS.NodeJS

macOS Installation

Method 1: Official Installer

1. Download `.pkg` from nodejs.org.
2. Open installer, continue, accept license, and install.
3. Enter Mac password when prompted.

Method 2: Homebrew

# Install Homebrew (if missing)
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
brew install node
node --version
npm --version
brew upgrade node

Method 3: NVM (Best for multiple versions)

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.0/install.sh | bash
source ~/.zshrc
nvm install --lts
nvm install 20.10.0
nvm use 20.10.0
nvm alias default 20.10.0
nvm list

How to Run Node.js on macOS

After installation, use Terminal to create and run your first Node.js program on macOS.

1) Verify Installation

node -v
npm -v

2) Create and Run a Simple File

mkdir mac-node-demo
cd mac-node-demo
printf "console.log('Hello from macOS Node.js');\n" > app.js
node app.js

3) Run an HTTP Server

printf "const http=require('http');const server=http.createServer((req,res)=>{res.end('Node on macOS works!');});server.listen(3000,()=>console.log('http://localhost:3000'));\n" > index.js
node index.js

Open http://localhost:3000 in your browser. For development workflow, initialize npm and use scripts: npm init -y, then npm start / npm run dev.

Linux Installation

Ubuntu/Debian

sudo apt update
sudo apt install nodejs npm
curl -fsSL https://deb.nodesource.com/setup_20.x | sudo -E bash -
sudo apt install -y nodejs
sudo apt install -y build-essential

Fedora/RHEL/CentOS

sudo dnf module enable nodejs:20
sudo dnf install nodejs npm
curl -sL https://rpm.nodesource.com/setup_20.x | sudo bash -
sudo yum install nodejs

Arch Linux

sudo pacman -S nodejs npm
yay -S nodejs

NVM (Any Linux)

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.0/install.sh | bash
source ~/.bashrc
nvm install --lts
nvm install 20.10.0
nvm use 20.10.0

Manual Binaries

wget https://nodejs.org/dist/v20.10.0/node-v20.10.0-linux-x64.tar.xz
tar -xf node-v20.10.0-linux-x64.tar.xz
sudo mv node-v20.10.0-linux-x64 /usr/local/node
export PATH=/usr/local/node/bin:$PATH
source ~/.bashrc

Verifying Installation

node --version
node -v
npm --version
npm -v

node
# > console.log("Hello, Node.js!");
# > .exit

npm help
# Windows
where node
where npm
# macOS/Linux
which node
which npm

NPM Deep Dive

NPM Architecture

+-----------------------------------------+
| NPM Registry (registry.npmjs.org)       |
+-------------------+---------------------+
                    |
                    v
+-----------------------------------------+
| package.json / node_modules / lockfile  |
+-----------------------------------------+

Create package.json

npm init
npm init -y

Common NPM Commands

Global vs Local Installation

Semantic Versioning

Version: 4.18.2
         | | +-- Patch
         | +---- Minor
         +------ Major

^4.18.2  # Compatible major
~4.18.2  # Compatible minor

Common Installation Issues & Solutions

Windows: "Node is not recognized"

Add `C:\Program Files\nodejs\` to PATH and restart terminal.

Windows: Global permission errors

npm config get prefix
mkdir ~\AppData\Roaming\npm-global
npm config set prefix ~\AppData\Roaming\npm-global

macOS: command not found / EACCES

export PATH="/usr/local/bin:$PATH"
echo 'export PATH="/usr/local/bin:$PATH"' >> ~/.zshrc
sudo chown -R $(whoami) ~/.npm

Linux: old version from package manager

curl -fsSL https://deb.nodesource.com/setup_20.x | sudo -E bash -
sudo apt install -y nodejs
# or use nvm install 20.10.0

First Project Setup

Create Project

mkdir my-first-node-app
cd my-first-node-app
git init
npm init -y

Create index.js

// index.js
console.log("Welcome to Node.js!");
const http = require('http');
const server = http.createServer((req, res) => {
    res.writeHead(200, { 'Content-Type': 'text/html' });
    res.write('<h1>Hello from Node.js!</h1>');
    res.write('<p>Your first server is running!</p>');
    res.end();
});
const PORT = 3000;
server.listen(PORT, () => {
    console.log(`Server running at http://localhost:${PORT}`);
});

Install Packages and Run

npm install express
npm install --save-dev nodemon
npm start
npm run dev

Project Structure Template

my-node-app/
|- node_modules/
|- src/
|  |- controllers/
|  |- models/
|  |- routes/
|  |- utils/
|- public/
|- tests/
|- .env
|- .gitignore
|- index.js
|- package.json

Sample .gitignore

node_modules/
npm-debug.log
.env
dist/
build/
.DS_Store
Thumbs.db
.vscode/
.idea/
coverage/

Yarn Alternative

npm install -g yarn
yarn init
yarn add express
yarn add --dev nodemon
yarn remove express

Contextual Learning Links

• HTML Tutorial - structure and semantics for web pages
• CSS Tutorial - styling concepts used in full-stack apps
• Bootstrap Tutorial - fast responsive UI building
• JavaScript Tutorial - core language foundation for Node.js

10 Interview Questions + 10 MCQs