Custom hooks extract and share component logic. Here's how to build them effectively.
Basic Custom Hook
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Hook with Parameters
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Async Hook with Loading State
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Hook Composition
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Reducer-Based Hook
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Testing Custom Hooks
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Best Practices
Naming:
✓ Start with "use" prefix
✓ Be descriptive
✓ Match React conventions
✓ Indicate return type
Design:
✓ Single responsibility
✓ Return stable references
✓ Handle cleanup
✓ Support SSR
Performance:
✓ Memoize callbacks
✓ Use lazy initialization
✓ Avoid unnecessary effects
✓ Handle race conditions
Testing:
✓ Test in isolation
✓ Test all states
✓ Test cleanup
✓ Test edge cases
Conclusion
Custom hooks encapsulate reusable logic cleanly. Start simple, compose smaller hooks into larger ones, and always handle cleanup. Test hooks in isolation using renderHook and consider all states: loading, success, error, and edge cases.