React Higher-Order Components (HOC)

A Higher-Order Component (HOC) is a function that takes a component and returns a new component with extra features.

1. Analogy ☕#

Think of a coffee cup (your component).
A HOC is like a sleeve you put around the cup: it doesn’t change the coffee, but it adds insulation (extra functionality).

2. Why Use HOCs?#

• Reusability → extract and share common logic.
• Separation of concerns → UI components stay simple, HOCs handle cross-cutting logic.
• Composition → wrap components with multiple behaviors.

3. Example#

// HOC that adds a loading spinner
function withLoading<P>(Component: React.ComponentType<P>) {
  return function WrappedComponent(props: P & { loading: boolean }) {
    if (props.loading) {
      return <div>Loading...</div>
    }
    return <Component {...props} />
  }
}

// Usage
function UserProfile({ name }: { name: string }) {
  return <h2>{name}</h2>
}

const UserProfileWithLoading = withLoading(UserProfile)

// Render
<UserProfileWithLoading loading={true} name="Alice" />

👉 If loading is true → show spinner. Otherwise, show UserProfile.

4. Common Use Cases#

• Auth wrapper → redirect if not logged in.
• Analytics wrapper → log component views.
• Data fetching → provide fetched data as props.
• UI wrappers → error boundaries, animations, styles.

5. Downsides#

• Can cause wrapper hell (too many nested HOCs).
• Makes React DevTools component tree messy.
• Harder to type with TypeScript.
• Modern React often prefers Hooks instead.

6. HOCs vs Hooks#

7. Quick Mental Model 🧠#

• HOC = function wrapper → adds behavior → returns new component.
• Use it for auth, logging, theming, analytics wrappers.
• Prefer hooks for most new code.

⚡ That’s it! HOCs are still useful in some cases, but hooks are the modern go-to for sharing React logic.