FrontendHaltReact·Advanced·Conceptual·1 min read
Why doesn't useMemo guarantee a value is never recalculated?
Short interview answer
React may choose to discard cached memoization results in some circumstances, such as under memory pressure, so useMemo should be treated as a performance hint rather than a semantic guarantee of calling the function only once per dependency change.
Key takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.