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---
description: Analyze and optimize bundle size
argument-hint:
allowed-tools: Bash, Read, Edit, MultiEdit
---
Analyze bundle size and optimize for production.
## Instructions
1. Run bundle analysis
2. Identify large dependencies
3. Find unused code
4. Implement optimization strategies
5. Generate optimization report
## Analysis Tools
### Next.js
```bash
# Install bundle analyzer
npm install -D @next/bundle-analyzer
# Configure next.config.js
const withBundleAnalyzer = require('@next/bundle-analyzer')({
enabled: process.env.ANALYZE === 'true',
})
module.exports = withBundleAnalyzer({
// your config
})
# Run analysis
ANALYZE=true npm run build
```
### Vite
```bash
# Install rollup plugin
npm install -D rollup-plugin-visualizer
# Add to vite.config.ts
import { visualizer } from 'rollup-plugin-visualizer'
plugins: [
visualizer({
open: true,
gzipSize: true,
brotliSize: true,
})
]
# Run build
npm run build
```
### General
```bash
# webpack-bundle-analyzer
npm install -D webpack-bundle-analyzer
# source-map-explorer
npm install -D source-map-explorer
npm run build
npx source-map-explorer 'build/static/js/*.js'
```
## Optimization Strategies
### 1. Code Splitting
```tsx
// Dynamic imports
const HeavyComponent = lazy(() => import('./HeavyComponent'))
// Route-based splitting (Next.js)
export default function Page() {
return <div>Auto code-split by route</div>
}
// Conditional loading
if (userNeedsFeature) {
const module = await import('./feature')
module.initialize()
}
```
### 2. Tree Shaking
```tsx
// ❌ Bad - imports entire library
import _ from 'lodash'
// ✅ Good - imports only what's needed
import debounce from 'lodash/debounce'
// For shadcn/ui - already optimized!
// Components are copied, not imported from package
```
### 3. Component Optimization
```tsx
// Memoize expensive components
const MemoizedComponent = memo(ExpensiveComponent)
// Lazy load heavy components
const Chart = lazy(() => import('./Chart'))
<Suspense fallback={<Skeleton />}>
<Chart />
</Suspense>
```
### 4. Asset Optimization
```tsx
// Next.js Image optimization
import Image from 'next/image'
<Image
src="/hero.jpg"
width={1200}
height={600}
priority
alt="Hero"
/>
// Font optimization
import { Inter } from 'next/font/google'
const inter = Inter({
subsets: ['latin'],
display: 'swap',
})
```
### 5. Dependency Optimization
```json
// Use lighter alternatives
{
"dependencies": {
// "moment": "^2.29.0", // 67kb
"date-fns": "^2.29.0", // 13kb (tree-shakeable)
// "lodash": "^4.17.0", // 71kb
"lodash-es": "^4.17.0", // Tree-shakeable
}
}
```
### 6. Tailwind CSS Optimization
```js
// tailwind.config.js
module.exports = {
content: [
// Be specific to avoid scanning unnecessary files
'./app/**/*.{js,ts,jsx,tsx}',
'./components/**/*.{js,ts,jsx,tsx}',
],
// Remove unused styles in production
purge: process.env.NODE_ENV === 'production' ? [
'./app/**/*.{js,ts,jsx,tsx}',
'./components/**/*.{js,ts,jsx,tsx}',
] : [],
}
```
## Optimization Checklist
- [ ] Enable production mode
- [ ] Remove console.logs and debug code
- [ ] Minify JavaScript and CSS
- [ ] Enable gzip/brotli compression
- [ ] Optimize images (WebP, AVIF)
- [ ] Lazy load non-critical resources
- [ ] Use CDN for static assets
- [ ] Implement caching strategies
- [ ] Remove unused dependencies
- [ ] Tree shake imports
## Report Format
```markdown
# Bundle Optimization Report
## Current Stats
- Total bundle size: XXXkb
- Gzipped size: XXXkb
- Largest chunks: [...]
## Issues Found
1. Large dependency: [package] (XXXkb)
2. Duplicate code in: [files]
3. Unused exports in: [modules]
## Optimizations Applied
1. ✅ Code split [component]
2. ✅ Lazy loaded [routes]
3. ✅ Replaced [heavy-lib] with [light-lib]
## Results
- Bundle size reduced by: XX%
- Initial load improved by: XXms
- Lighthouse score: XX → XX
## Recommendations
1. Consider replacing...
2. Lazy load...
3. Split chunk for...
```
## Example
If the user says: `/optimize-bundle`
1. Analyze current bundle size
2. Identify optimization opportunities:
- Large dependencies to replace
- Components to lazy load
- Unused code to remove
3. Implement optimizations
4. Re-analyze and compare results
5. Generate detailed report
|
