React · Senior · Question 73 of 75

Why might `onClick={() => select(item.id)}` defeat `memo` on 1000 list rows?

✓Correct answer: Each render creates new functions for every row, so all memoized rows see changed props
2Arrow functions are slower to call
3memo doesn't work with lists

Explanation

Pass a stable onSelect (via useCallback) and the id as separate props; the row calls onSelect(id). The React Compiler can automate this.

Further reading

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