Quiz for useCallback

Q1: What is the primary purpose of the useCallback hook?

A. To memoize functions B. To manage state C. To fetch data D. To perform side effects

Q2: When does useCallback return a new function?

A. Every render B. Only when dependencies change C. Only on mount D. Never

Q3: How do you use useCallback?

A. const memoFn = useCallback(() => { }, [deps]) B. const memoFn = useCallback() C. const memoFn = useState() D. const memoFn = useEffect()

Q4: What problem does useCallback solve?

A. Avoiding unnecessary function recreations causing re-renders B. Managing local state C. Data fetching D. Event handling

Q5: What is a common use case for useCallback?

A. Passing stable callbacks to optimized child components B. Fetching API data C. Managing forms D. Styling components

Q6: Which hook is often used together with useCallback?

A. useMemo B. useState C. useEffect D. useRef

Q7: How is useCallback different from useMemo?

A. useCallback memoizes functions, useMemo memoizes values B. useMemo memoizes functions, useCallback memoizes values C. They do the same D. useCallback is deprecated

Q8: Does useCallback cause component re-renders?

A. No, but it helps prevent child re-renders B. Yes, always C. Only with useState D. Only with useEffect

Q9: What happens if you pass an empty dependency array to useCallback?

A. Function is memoized once and never changes B. Function changes every render C. Throws an error D. Function is recreated every render

Q10: Can useCallback be used to optimize expensive functions?

A. Yes, if those functions are passed as props B. No, it’s only for event handlers C. No, it’s for state updates D. Only for class components

Q11: Is useCallback necessary if you do not pass functions as props?

A. Usually no B. Yes, always C. Only in class components D. Only with Redux

Q12: What should you avoid when using useCallback?

A. Adding too many dependencies unnecessarily B. Using it with state C. Using it in class components D. Using it inside loops

Q13: Can useCallback be used inside loops or conditions?

A. No, hooks must be called unconditionally B. Yes, always C. Only in class components D. Only with useState

Q14: Does useCallback memoize the return value of the function?

A. No, it memoizes the function reference B. Yes C. Only sometimes D. Only with useMemo

Q15: What is the return type of useCallback?

A. Memoized function B. Value C. State updater D. React element

Q16: What is the risk of not using useCallback when passing functions as props?

A. Unnecessary child component rerenders B. State loss C. Memory leaks D. API failures

Q17: Can useCallback help with React.memo?

A. Yes, by providing stable function props B. No C. Only in class components D. Only with useEffect

Q18: Does useCallback replace the need for useMemo?

A. No, they serve different purposes B. Yes, always C. Only in functional components D. Only in class components

Q19: What happens if you forget dependencies in useCallback?

A. Function may reference stale values B. Function updates correctly C. Error is thrown D. Component crashes

Q20: Is useCallback useful for inline event handlers?

A. Yes, to prevent unnecessary recreations B. No, it slows down C. Only for API calls D. Only in class components