Node.js and npm - Fundamentals

Welcome! Before we start building applications with Next.js, you need to install two key tools: Node.js and npm.

What is Node.js?

Node.js is a JavaScript runtime environment outside the browser. Thanks to it, you can run JavaScript code on your computer, not just in the browser.

Why is Node.js important?

• Running Next.js requires Node.js
• Installing packages (libraries)
• Developer tools (build tools)
• Development server (localhost)

What is npm?

npm (Node Package Manager) is a package manager for JavaScript. It allows you to install libraries and tools created by other developers.

Examples of npm packages:

• react - library for building UI
• next - Next.js framework
• tailwindcss - CSS framework
• Millions more...

Installing Node.js and npm

Node.js and npm are installed together - one installer, two tools.

Step 1: Download the installer

1. Go to: https://nodejs.org and click Get Node.js®
2. On the download page, keep the version marked LTS (Long Term Support, v24 today) in the menu ← Choose this one! The Current version (v26 today) has the newest features but shorter support.
3. Further down, under "Or get a prebuilt Node.js®", click the installer button for your system (Windows: .msi, macOS: .pkg)

Step 2: Install

Windows:

• Double-click the .msi file
• Click "Next" → "Next" → "Install"
• Wait ~1-2 minutes

Mac:

• Double-click the .pkg file
• Click "Continue" → "Install"
• Wait ~1-2 minutes

Linux (Ubuntu/Debian):

curl -fsSL https://deb.nodesource.com/setup_lts.x | sudo -E bash -
sudo apt-get install -y nodejs

Step 3: Verification

Open the terminal in Cursor (Ctrl + `, on a Mac also Control, not Cmd) and type:

node --version

You should see something like: v24.21.0 (the current LTS version). Next.js 16 needs at least version 20.9.

Check npm:

npm --version

You should see something like: 11.19.0 (the npm that comes with Node.js 24).

If you see version numbers - congratulations! Node.js and npm are installed.

Basic npm commands

Now that you have npm, you can install packages and run projects.

1. npm install - Installing packages

When you open an existing Next.js project, the first step is to install dependencies:

npm install

This downloads all libraries listed in package.json.

2. npm run dev - Development server

This starts the Next.js development server:

npm run dev

After this, your application will be available at http://localhost:3000

3. npm run build - Building for production

This prepares the application for deployment:

npm run build

4. npx - Running tools without installation

npx allows you to run tools without global installation:

npx create-next-app@latest

This will create a new Next.js project.

package.json - The Heart of the Project

Every JavaScript project has a package.json file - it's like the project's ID card.

It contains:

• Project name
• List of dependencies
• Scripts - npm commands
• Metadata (author, description, license)

Example package.json:

{
  "name": "krakens-call",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "dev": "next dev",
    "build": "next build",
    "start": "next start",
    "lint": "eslint"
  },
  "dependencies": {
    "next": "16.3.8",
    "react": "19.2.8",
    "react-dom": "19.2.8"
  }
}

Scripts are commands you can run via npm run:

• npm run dev → runs next dev
• npm run build → runs next build

node_modules - The Libraries Folder

When you run npm install, npm creates a node_modules folder with all installed packages.

IMPORTANT:

• node_modules can be hundreds of MB or more
• DO NOT commit node_modules to Git
• Add node_modules/ to .gitignore
• Each person downloads the project and runs npm install

Summary

Node.js - runtime for executing JavaScript npm - package manager package.json - list of dependencies and scripts node_modules - folder with installed packages npm install - installs dependencies npm run dev - starts development server npx - runs tools without installation

In the next exercise we'll create our first Next.js project!

See you there!