← Practice
Arrays·medium 18 min 75 XP

Unique Values by Key

Given an array of objects, return one object per distinct value of a given key, keeping the first occurrence.

Examples

  • uniqueByKey([{id:1},{id:1},{id:2}], "id") → [{id:1},{id:2}]

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
Unique Values by Key · editor

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