Building Scalable React Applications

As a MERN stack developer who's built multiple production applications, I've learned that writing React code is easy—writing scalable React code is an art. Today, I'm sharing the architecture patterns and best practices I use in every project.

The Problem with "Just Start Coding"

When I built my first React app, I threw everything into components without thinking about structure. Fast forward three months, and I was drowning in prop drilling, duplicate logic, and components that did way too much.

Sound familiar?

1. Folder Structure That Scales

Here's the structure I use for all my React projects now:

src/
├── components/
│   ├── common/          # Reusable UI components
│   ├── layout/          # Layout components
│   └── features/        # Feature-specific components
├── hooks/               # Custom hooks
├── context/             # Context providers
├── services/            # API calls
├── utils/               # Helper functions
├── constants/           # Constants and configs
└── pages/               # Page components

Why this works: Each folder has a single responsibility. When I need to find something, I know exactly where to look.

2. Component Composition Over Complexity

I learned this the hard way. Here's a component from my early days:

// ❌ Bad: God component doing everything
function UserDashboard() {
  const [user, setUser] = useState(null);
  const [posts, setPosts] = useState([]);
  const [loading, setLoading] = useState(true);
  
  // 200 lines of logic...
  
  return (
    <div>
      {/* 300 lines of JSX */}
    </div>
  );
}

Now I break it down:

// ✅ Good: Composed components
function UserDashboard() {
  return (
    <DashboardLayout>
      <UserProfile />
      <UserStats />
      <UserPosts />
    </DashboardLayout>
  );
}

Rule of thumb: If your component is over 150 lines, it's probably doing too much.

3. Custom Hooks for Logic Reuse

Custom hooks changed my life. Instead of copying logic between components, I extract it:

// hooks/useAuth.js
export function useAuth() {
  const [user, setUser] = useState(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    const unsubscribe = auth.onAuthStateChanged(setUser);
    setLoading(false);
    return unsubscribe;
  }, []);

  return { user, loading };
}

I use custom hooks for:

• API calls (useFetch, useApi)
• Form handling (useForm)
• Local storage (useLocalStorage)
• Debouncing (useDebounce)

4. State Management: Keep It Simple

I see developers reaching for Redux immediately. Here's my approach:

1. Local state for component-specific data
2. Context for app-wide data (theme, auth)
3. Redux/Zustand only when Context becomes messy

For my e-commerce project, I used Context for cart and auth. That's it. No Redux needed.

5. Performance Optimization

Three techniques I use in every project:

Code Splitting

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

function App() {
  return (
    <Suspense fallback={<Loading />}>
      <Dashboard />
    </Suspense>
  );
}

Memoization

const ExpensiveComponent = memo(({ data }) => {
  return <div>{/* Heavy computation */}</div>;
});

Key Takeaways

1. Structure matters - Organize by feature, not file type
2. Compose, don't complicate - Small, focused components
3. Extract logic - Custom hooks are your friend
4. Optimize smartly - Measure before optimizing
5. Plan for errors - Error boundaries save production

Want to see these patterns in action? Check out my projects on GitHub.