function useFriendStatus(friendID) const [isOnline, setIsOnline] = useState(null); useDebugValue(isOnline ? 'Online' : 'Offline'); return isOnline;
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]); advanced hook
Enter . These are not just obscure APIs; they are architectural patterns and built-in tools ( useReducer , useCallback , useMemo , useRef , useLayoutEffect , useImperativeHandle , useDebugValue , and custom hooks) that, when mastered, transform your code from "working" to elegant, predictable, and highly performant . A custom hook is a JavaScript function whose
return results, isLoading ;