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Mutation vs immutable copy for shared JavaScript state

Guided tradeoff battle · Updated Mar 29, 2026

A UI updates nested client-side state and also needs undo, predictable re-renders, and easy debugging. Would you mutate existing objects or create immutable copies?

  • Mutate existing state
  • Create immutable copies

Challenge preview

Mutation vs immutable copy for shared JavaScript state: commit to a direction, justify it with the prompt constraints, and explain when the alternative wins.

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  • Rubric for explaining when the alternative becomes stronger.

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