React Vite Best Practices

---
name: react-vite-best-practices
description: React and Vite performance optimization guidelines. Use when writing, reviewing, or optimizing React components built with Vite. Triggers on tasks involving Vite configuration, build optimization, code splitting, lazy loading, HMR, bundle size, or React performance.
license: MIT
metadata:
  author: agent-skills
  version: "2.0.0"
---

# React + Vite Best Practices

Comprehensive performance optimization guide for React applications built with Vite. Contains 23 rules across 6 categories for build optimization, code splitting, development performance, asset handling, environment configuration, and bundle analysis.

## Metadata

- **Version:** 2.0.0
- **Framework:** React + Vite
- **Rule Count:** 23 rules across 6 categories
- **License:** MIT

## When to Apply

Reference these guidelines when:
- Configuring Vite for React projects
- Implementing code splitting and lazy loading
- Optimizing build output and bundle size
- Setting up development environment and HMR
- Handling images, fonts, SVGs, and static assets
- Managing environment variables across environments
- Analyzing bundle size and dependencies

## Rule Categories by Priority

| Priority | Category | Impact | Prefix |
|----------|----------|--------|--------|
| 1 | Build Optimization | CRITICAL | `build-` |
| 2 | Code Splitting | CRITICAL | `split-` |
| 3 | Development | HIGH | `dev-` |
| 4 | Asset Handling | HIGH | `asset-` |
| 5 | Environment Config | MEDIUM | `env-` |
| 6 | Bundle Analysis | MEDIUM | `bundle-` |

## Quick Reference

### 1. Build Optimization (CRITICAL)

- `build-manual-chunks` - Configure manual chunks for vendor separation
- `build-minification` - Minification with OXC (default) or Terser
- `build-target-modern` - Target modern browsers (baseline-widely-available)
- `build-sourcemaps` - Configure sourcemaps per environment
- `build-tree-shaking` - Ensure proper tree shaking with ESM
- `build-compression` - Gzip and Brotli compression
- `build-asset-hashing` - Content-based hashing for cache busting

### 2. Code Splitting (CRITICAL)

- `split-route-lazy` - Route-based splitting with React.lazy()
- `split-suspense-boundaries` - Strategic Suspense boundary placement
- `split-dynamic-imports` - Dynamic import() for heavy components
- `split-component-lazy` - Lazy load non-critical components
- `split-prefetch-hints` - Prefetch chunks on hover/idle/viewport

### 3. Development (HIGH)

- `dev-dependency-prebundling` - Configure optimizeDeps for faster starts
- `dev-fast-refresh` - React Fast Refresh patterns
- `dev-hmr-config` - HMR server configuration

### 4. Asset Handling (HIGH)

- `asset-image-optimization` - Image optimization and lazy loading
- `asset-svg-components` - SVGs as React components with SVGR
- `asset-fonts` - Web font loading strategy
- `asset-public-dir` - Public directory vs JavaScript imports

### 5. Environment Config (MEDIUM)

- `env-vite-prefix` - VITE_ prefix for client variables
- `env-modes` - Mode-specific environment files
- `env-sensitive-data` - Never expose secrets in client code

### 6. Bundle Analysis (MEDIUM)

- `bundle-visualizer` - Analyze bundles with rollup-plugin-visualizer

## Essential Configurations

### Recommended vite.config.ts

```typescript
import { defineConfig } from 'vite'
import react from '@vitejs/plugin-react'
import path from 'path'

export default defineConfig({
  plugins: [react()],

  resolve: {
    alias: {
      '@': path.resolve(__dirname, './src'),
    },
  },

  build: {
    target: 'baseline-widely-available',
    sourcemap: false,
    chunkSizeWarningLimit: 500,
    rollupOptions: {
      output: {
        manualChunks: {
          vendor: ['react', 'react-dom'],
        },
      },
    },
  },

  optimizeDeps: {
    include: ['react', 'react-dom'],
  },

  server: {
    port: 3000,
    hmr: {
      overlay: true,
    },
  },
})
```

### Route-Based Code Splitting

```typescript
import { lazy, Suspense } from 'react'

const Home = lazy(() => import('./pages/Home'))
const Dashboard = lazy(() => import('./pages/Dashboard'))
const Settings = lazy(() => import('./pages/Settings'))

function App() {
  return (
    <Suspense fallback={<LoadingSpinner />}>
      {/* Routes here */}
    </Suspense>
  )
}
```

### Environment Variables

```typescript
// src/vite-env.d.ts
/// <reference types="vite/client" />

interface ImportMetaEnv {
  readonly VITE_API_URL: string
  readonly VITE_APP_TITLE: string
}

interface ImportMeta {
  readonly env: ImportMetaEnv
}
```

## How to Use

Read individual rule files for detailed explanations and code examples:

```
rules/build-manual-chunks.md
rules/split-route-lazy.md
rules/env-vite-prefix.md
```

## References

- [Vite Documentation](https://vite.dev)
- [React Documentation](https://react.dev)
- [Rollup Documentation](https://rollupjs.org)

## Full Compiled Document

For the complete guide with all rules expanded: `AGENTS.md`