← Practice
DOM·easy 10 min 50 XP

Counter Logic

Write createCounter(start) returning { increment, decrement, value } — the state logic behind a UI counter button.

Examples

  • const c = createCounter(0); c.increment(); c.value() → 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
Counter Logic · editor

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