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DOM·medium 18 min 75 XP

Dynamic List Reducer

Write applyListAction(items, action) supporting {type:'add',item} and {type:'remove',id} — the state logic behind a dynamic UI list.

Examples

  • applyListAction([], { type: 'add', item: { id: 1 } }) → [{ id: 1 }]

Constraints

  • Keep the required function name so the tests can find it
  • Return a value instead of only logging it
  • Do not mutate inputs unless the challenge asks you to
Dynamic List Reducer · editor

Code runs in an isolated Web Worker with a 3-second timeout — no DOM access, and it can never hang the page.