Turbopack Bundler

Development Mode

# Next.js 13.4+
next dev --turbo

# Or in package.json
{
  "scripts": {
    "dev": "next dev --turbo"
  }
}

Next.js Configuration

// next.config.js
module.exports = {
  experimental: {
    turbo: {
      // Turbopack-specific configuration
    }
  }
};

Configuration Options

Custom Loaders

// next.config.js
module.exports = {
  turbopack: {
    rules: {
      '*.svg': {
        loaders: ['@svgr/webpack'],
        as: '*.js'
      },
      '*.mdx': {
        loaders: ['@mdx-js/loader']
      }
    }
  }
};

Resolve Aliases

// next.config.js
module.exports = {
  turbopack: {
    resolveAlias: {
      '@components': './src/components',
      '@lib': './src/lib',
      '@styles': './src/styles'
    }
  }
};

Resolve Extensions

// next.config.js
module.exports = {
  turbopack: {
    resolveExtensions: ['.tsx', '.ts', '.jsx', '.js', '.json']
  }
};

Built-in Support

Turbopack has built-in support for:

• TypeScript: No configuration needed
• JSX/TSX: Automatic transformation
• CSS: Native CSS support
• CSS Modules: .module.css files
• PostCSS: Automatic processing
• Static Assets: Images, fonts, etc.

No loaders needed for:

• css-loader
• postcss-loader
• babel-loader (for @babel/preset-env)

TypeScript Configuration

Recommended tsconfig.json

{
  "compilerOptions": {
    "target": "ES2017",
    "lib": ["dom", "dom.iterable", "esnext"],
    "allowJs": true,
    "skipLibCheck": true,
    "strict": true,
    "noEmit": true,
    "esModuleInterop": true,
    "module": "esnext",
    "moduleResolution": "bundler",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "jsx": "preserve",
    "incremental": true,
    "baseUrl": ".",
    "paths": {
      "@/*": ["./src/*"]
    }
  }
}

Path Aliases

{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "@components/*": ["src/components/*"],
      "@lib/*": ["src/lib/*"],
      "@styles/*": ["src/styles/*"]
    }
  }
}

Code Organization

Atomic Design Pattern

src/
├── components/
│   ├── atoms/          # Basic building blocks
│   │   ├── Button/
│   │   └── Input/
│   ├── molecules/      # Combinations of atoms
│   │   ├── SearchBar/
│   │   └── NavItem/
│   ├── organisms/      # Complex components
│   │   ├── Header/
│   │   └── Footer/
│   └── templates/      # Page layouts
│       └── MainLayout/
├── app/
│   └── page.tsx
└── lib/
    └── utils.ts

Component Structure

Button/
├── Button.tsx
├── Button.module.css
├── Button.test.tsx
└── index.ts

Code Splitting

Dynamic Imports

import dynamic from 'next/dynamic';

const HeavyComponent = dynamic(() => import('@/components/HeavyComponent'), {
  loading: () => <p>Loading...</p>,
  ssr: false // Disable server-side rendering if needed
});

Route-Based Splitting

Next.js automatically code-splits by route in the app/ directory.

Manual Splitting

// Split large components
const ChartComponent = dynamic(() => import('./ChartComponent'));
const EditorComponent = dynamic(() => import('./EditorComponent'));

Caching Strategy

Turbo Engine Caching

• Function-level caching for incremental builds
• Only recomputes what changed
• Persistent cache across builds

Optimizing for Cache

// Keep modules focused and small
// Changes to one module don't invalidate others

// Good: Separate concerns
export function formatDate(date: Date) { /* ... */ }
export function formatCurrency(amount: number) { /* ... */ }

// Avoid: Large utility files that change frequently

Performance Best Practices

Module Organization

• Keep modules small and focused
• Minimize cross-module dependencies
• Use barrel exports sparingly

Import Optimization

// Prefer specific imports
import { Button } from '@/components/Button';

// Avoid importing entire libraries
// Bad: import _ from 'lodash';
// Good: import debounce from 'lodash/debounce';

Static Analysis

// Use const assertions for better tree-shaking
const ROUTES = {
  home: '/',
  about: '/about',
  contact: '/contact'
} as const;

CSS Handling

CSS Modules

import styles from './Component.module.css';

function Component() {
  return <div className={styles.container}>Content</div>;
}

Global CSS

// app/layout.tsx
import './globals.css';

Tailwind CSS

// tailwind.config.js
module.exports = {
  content: [
    './src/**/*.{js,ts,jsx,tsx,mdx}',
    './app/**/*.{js,ts,jsx,tsx,mdx}'
  ]
};

Environment Variables

Next.js Environment Variables

# .env.local
NEXT_PUBLIC_API_URL=https://api.example.com
DATABASE_URL=postgresql://...

// Client-side (must have NEXT_PUBLIC_ prefix)
const apiUrl = process.env.NEXT_PUBLIC_API_URL;

// Server-side only
const dbUrl = process.env.DATABASE_URL;

Testing

Test Organization

src/
├── components/
│   └── Button/
│       ├── Button.tsx
│       └── Button.test.tsx    # Co-located test
└── __tests__/                 # Integration tests
    └── pages/
        └── home.test.tsx

Testing Best Practices

• Write unit tests for utility functions
• Use React Testing Library for components
• End-to-end tests with Cypress or Playwright
• Keep tests close to the code they test

Common Pitfalls

Configuration Issues

// Ensure correct tsconfig.json paths
{
  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "@/*": ["./src/*"]  // Must match actual structure
    }
  }
}

Caching Problems

# Clear Turbopack cache if issues arise
rm -rf .next

Compatibility

• Check dependency compatibility with Turbopack
• Some webpack plugins may not work directly
• Use Next.js configuration instead of webpack config

Migration from Webpack

What Changes

• No direct webpack.config.js
• Use next.config.js for customization
• Some loaders need Turbopack equivalents

What Stays the Same

• Import syntax
• Dynamic imports
• CSS Modules
• TypeScript support

Best Practices Summary

Do

• Use Next.js configurations for customization
• Leverage built-in TypeScript and JSX support
• Organize code for incremental computation
• Use dynamic imports for code splitting
• Keep modules focused and small

Avoid

• Direct webpack configurations
• Large barrel files that change frequently
• Fighting against Next.js conventions
• Ignoring TypeScript path configuration

Debugging

Verbose Logging

NEXT_DEBUG_TURBOPACK=1 next dev --turbo

Build Analysis

# Check build output
ANALYZE=true next build

Common Issues

1. Slow initial build: Normal, subsequent builds are fast
2. Module not found: Check path aliases in tsconfig.json
3. CSS not loading: Ensure proper import syntax
4. Type errors: Run tsc --noEmit separately