Mastering React: Best Practices for 2025

Modern React in 2025

React 19 introduces Server Components, Actions, and improved concurrency. Here are the best practices for building performant, maintainable applications.

1. Server Components by Default

// app/page.tsx - Server Component by default
async function Page() {
  const data = await db.query('SELECT * FROM posts');
  return ;
}

Only use 'use client' when you need interactivity (hooks, browser APIs).

2. Use Server Actions for Mutations

'use server';

export async function createPost(formData: FormData) {
  const title = formData.get('title');
  await db.insert('posts', { title });
  revalidatePath('/posts');
}

Eliminates API routes for simple mutations. Works with progressive enhancement.

3. Suspense for Data Fetching

}>

Streaming SSR with granular loading states. No more waterfall requests.

4. Compound Components Pattern

const Tabs = ({ children, defaultIndex = 0 }) => {
  const [active, setActive] = useState(defaultIndex);
  return (
    
      {children}
    
  );
};

Flexible APIs that prevent prop drilling and improve composability.

5. Custom Hooks for Logic Reuse

function useLocalStorage(key, initialValue) {
  const [value, setValue] = useState(() => {
    const stored = localStorage.getItem(key);
    return stored ? JSON.parse(stored) : initialValue;
  });

  useEffect(() => {
    localStorage.setItem(key, JSON.stringify(value));
  }, [key, value]);

  return [value, setValue];
}

6. Performance Optimization

React.memo for expensive components
useMemo/useCallback for stable references
Virtualize long lists with @tanstack/react-virtual
Code-split with React.lazy and Suspense

7. State Management: Less is More

Local state: useState, useReducer
Shared state: Context + useReducer
Global state: Zustand, Jotai (lightweight)
Server state: TanStack Query (React Query)

8. TypeScript Best Practices

interface Props {
  // Prefer interfaces for public APIs
  onSubmit: (data: FormData) => Promise;
  // Discriminated unions for variants
  variant: 'primary' | 'secondary' | 'ghost';
}

9. Testing Strategy

Unit: Custom hooks, utilities (Vitest)
Component: React Testing Library
Integration: User flows, API mocking (MSW)
E2E: Critical paths only (Playwright)

10. Accessibility by Default

Semantic HTML always
ARIA labels only when necessary
Focus management in modals/drawers
Color contrast ratios (WCAG AA)
Test with screen readers