Advanced Hook Extra Quality Review

function useFriendStatus(friendID) const [isOnline, setIsOnline] = useState(null); useDebugValue(isOnline ? 'Online' : 'Offline'); return isOnline;

Now in DevTools, your hook displays FriendStatus: "Online" instead of an opaque value. Consider a dashboard that subscribes to a WebSocket stream, processes messages with expensive filtering, and exposes controls to pause/resume. advanced hook

return data: processedData, pause: () => setIsPaused(true), resume: () => setIsPaused(false) ; It allows you to extract component logic into

This keeps the child’s internal implementation private while exposing only the necessary imperative API. The pinnacle of advanced hooks is creating your own. A custom hook is a JavaScript function whose name starts with use and may call other hooks. It allows you to extract component logic into reusable, testable units. Example: useDebouncedSearch function useDebouncedSearch(query, delay = 300) const [results, setResults] = useState([]); const [isLoading, setIsLoading] = useState(false); useEffect(() => if (!query) return; const handler = setTimeout(async () => setIsLoading(true); const data = await searchAPI(query); setResults(data); setIsLoading(false); , delay); return () => clearTimeout(handler); , [query, delay]); delay = 300) const [results

return results, isLoading ;

| Anti-Pattern | Why It’s Bad | Better Approach | |--------------|---------------|------------------| | Overly broad dependencies in useCallback | Memoization breaks on every render | Break logic into smaller hooks or use useReducer | | useMemo for simple arithmetic | Wastes memory and CPU | Let it compute; it’s cheap | | useLayoutEffect for data fetching | Blocks paint unnecessarily | useEffect + loading state | | Custom hook that causes cascade re-renders | Returns new object/array each call | Memoize returned object with useMemo | When building custom hooks, React DevTools shows generic "CustomHook" entries. Make them useful with useDebugValue :

const FancyInput = forwardRef((props, ref) => const inputRef = useRef(); useImperativeHandle(ref, () => ( focus: () => inputRef.current.focus(), clear: () => inputRef.current.value = ''; , shake: () => /* animation logic */ )); return <input ref=inputRef ...props />; ); // Parent usage: const ref = useRef(); <FancyInput ref=ref /> ref.current.shake();