React useMemo for Performance MCQ useMemo Optimization Practice Questions

Direction: Choose the correct option

How does useMemo help with performance?

A. By memoizing expensive calculations so they don't run on every render

B. By caching API responses

C. By preventing re-renders

D. By memoizing components

Direction: Choose the correct option

When should you use useMemo for performance?

A. For state updates

B. For expensive computations that are likely to be a bottleneck

C. For simple arithmetic

D. For all values

Direction: Choose the correct option

What is the difference between useMemo and React.memo?

A. React.memo is for functions

B. useMemo is for class components

C. They are the same

D. useMemo memoizes values, React.memo memoizes components

Direction: Choose the correct option

Given a list filter operation, when would you use useMemo?

A. Only when the list is small

B. Always

C. When filtering a large array to avoid re-filtering on every render

D. Never

Direction: Choose the correct option

What happens if the dependencies of useMemo are not specified correctly?

A. It throws an error

B. It uses default values

C. It always recomputes

D. The memoized value may become stale or not update when needed

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