React useMemo Hook MCQ useMemo Practice Questions

Direction: Choose the correct option

What is the purpose of the useMemo hook?

A. To create refs

B. To handle side effects

C. To memoize functions

D. To memoize expensive computations

Direction: Choose the correct option

What does useMemo return?

A. A ref

B. A state variable

C. A memoized value

D. A memoized function

Direction: Choose the correct option

When should you use useMemo?

A. For expensive calculations that you don't want to recompute on every render

B. For all functions

C. For every variable

D. For state updates

Direction: Choose the correct option

What happens if the dependencies array is empty?

A. The value is computed only once

B. It throws an error

C. The value is computed on every render

D. The value never updates

Direction: Choose the correct option

Given const computed = useMemo(() => expensive(a, b), [a, b]); When does expensive re-run?

A. Only when a or b change

B. On every render

C. Only when a changes

D. Only when b changes

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