🚀 Next.js CLI (Command Line Interface)

The Next.js CLI (next) is used to manage and run a Next.js application efficiently. It provides commands for development, building, starting the production server, and more.

📌 1. Running Next.js in Development

🔹 Start the Dev Server

bash
npm run dev# ORyarn dev# ORpnpm dev

• Runs the Next.js development server on http://localhost:3000

• Supports hot reloading and error reporting

Custom Port:

bash
next dev -p 4000

• Starts the server on http://localhost:4000

📌 2. Building for Production

🔹 Create a Production Build

bash
npm run build# ORyarn build# ORpnpm build

• Compiles and optimizes the app

• Generates static HTML (for SSG pages) and server-side assets

📌 3. Running in Production

🔹 Start the Production Server

bash
npm run start# ORyarn start# ORpnpm start

• Runs the optimized Next.js app on http://localhost:3000

Custom Port:

bash
next start -p 5000

• Starts the server on http://localhost:5000

📌 4. Exporting as Static Files

🔹 Export Static Site

If your app uses Static Site Generation (SSG), you can export it to a fully static site:

bash
npm run export# ORyarn export# ORpnpm export

• Generates a out/ directory with static HTML files

• Useful for static hosting (Netlify, GitHub Pages, Vercel)

📌 5. Linting & Formatting

🔹 Run ESLint

bash
npm run lint# ORyarn lint# ORpnpm lint

• Checks for code errors and best practices

🔹 Run Prettier Formatting

bash
npx prettier --write .

• Auto-formats your code

📌 6. Checking App Performance

🔹 Run Next.js Analytics

bash
npm run analyze

• Shows bundle size and performance insights

To enable, modify next.config.js:

javascript
const withBundleAnalyzer = require('@next/bundle-analyzer')({  enabled: process.env.ANALYZE === 'true',});module.exports = withBundleAnalyzer({});

Then run:

bash
ANALYZE=true npm run build

📌 7. Running Custom Scripts

You can create custom scripts in package.json:

jso
"scripts": {  "dev": "next dev",  "build": "next build",  "start": "next start",  "lint": "next lint",  "export": "next export"}

Now, just run:

bash
npm run build

📌 8. Environment Variables in CLI

Run the app with a specific environment variable:

bash
NEXT_PUBLIC_API_URL="https://api.example.com" next dev

Or define a .env.local file:

env
NEXT_PUBLIC_API_URL=https://api.example.com

And access it in Next.js:

javascript
console.log(process.env.NEXT_PUBLIC_API_URL);

📌 9. Installing Dependencies

🔹 Install a Package

bash
npm install axios# ORyarn add axios# ORpnpm add axios

🔹 Remove a Package

bash
npm uninstall axios# ORyarn remove axios# ORpnpm remove axios

📌 10. Running Tests

If you use Jest or Cypress, you can run tests:

bash
npm run test

Or for e2e testing:

bash
npm run cypress

🚀 Summary of Next.js CLI Commands