modern react

# modern react

## modern react best practices

### 1. project structure
- use a feature-based structure (e.g., features/, components/, hooks/, utils/)
- separate concerns: logic in hooks, UI in components
- colocate component-specific styles and tests within the component folder

### 2. state management
- use `useContext` + `useReducer` for global state instead of prop drilling
- prefer Zustand or Jotai over Redux for lightweight state
- Recoil is useful for atomic state updates
- keep UI state local whenever possible

### 3. performance optimizations
- use `React.memo` for memoizing components
- use `useCallback` to memoize event handlers
- use `useMemo` to memoize computed values
- avoid unnecessary re-renders by carefully managing dependencies in `useEffect`
- prefer lazy loading with `React.lazy` and `Suspense` for large components
- enable automatic batching in React 18
- use React Profiler and the Chrome DevTools for performance debugging

### 4. hooks best practices
- follow the rules of hooks (only call hooks at the top level, only in function components)
- extract reusable logic into custom hooks
- debounce expensive effects using `useDebounce`
- manage async calls using `useEffect` with cleanup
- prefer `useRef` over `useState` to store mutable values without re-rendering

### 5. forms and controlled components
- use `react-hook-form` for lightweight, performant forms
- prefer controlled inputs over uncontrolled for consistency
- leverage Yup/Zod for schema validation
- debounce form submissions using `useDebounce`

### 6. server-side communication
- use React Query or SWR for data fetching and caching
- prefer GraphQL (Apollo/Urql) over REST when appropriate
- implement optimistic updates for better UX
- use `Suspense` for data fetching in future-proof applications
- normalize API responses using Zod or custom transformers

### 7. styling best practices
- prefer Tailwind CSS for utility-based styling
- use CSS Modules or Styled Components for scoped styles
- avoid inline styles for dynamic styling to prevent unnecessary re-renders
- use theme providers for global theming

### 8. testing best practices
- use Jest + React Testing Library for unit and integration testing
- write end-to-end (E2E) tests with Playwright or Cypress
- mock network requests using MSW (Mock Service Worker)
- follow the AAA (Arrange, Act, Assert) pattern in tests
- prefer testing behavior over implementation details

### 9. accessibility (a11y)
- use `@testing-library/jest-dom` for accessibility assertions
- prefer semantic HTML elements (e.g., `<button>`, `<label>`, `<nav>`)
- ensure keyboard navigation support
- use aria attributes where necessary
- test with screen readers

### 10. error handling and logging
- use Error Boundaries for catching UI errors
- log errors with Sentry, LogRocket, or `console.error`
- display meaningful error messages to users
- handle API failures gracefully with fallback UI

### 11. routing best practices
- use React Router v6+
- prefer nested routes for complex layouts
- use lazy loading with dynamic imports for route-based code splitting
- manage auth-based routes with ProtectedRoute components

### 12. deployment and production optimization
- enable tree shaking and code splitting
- use Vite for faster builds over Webpack
- leverage SSR (Next.js) for SEO and initial load performance
- prefetch data using `useQuery.prefetch` or `getStaticProps`
- use CDNs for asset delivery
- optimize images using `next/image` or responsive formats
- serve gzip or brotli compressed assets

### 13. security best practices
- sanitize user input to prevent XSS attacks
- use helmet for securing headers
- never expose API keys in client-side code
- validate backend responses with Zod
- implement rate limiting and authentication guards

### 14. future-proofing with react 18+
- use concurrent rendering for better responsiveness
- leverage `useTransition` and `useDeferredValue` for smoother UI updates
- prefer `useId` over manually managing unique IDs

### 15. recommended tools & libraries
- state management: Zustand, Jotai, Recoil
- forms: React Hook Form + Yup/Zod
- fetching: React Query, SWR
- UI: Tailwind CSS, shadcn/ui, Material UI
- testing: Jest, React Testing Library, MSW, Playwright
- logging: Sentry, LogRocket
- deployment: Vercel, Netlify, Docker

this guide provides a comprehensive approach to writing modern, maintainable react applications with best practices in mind.