Why does my useEffect run twice in development?

Asked 5 days agoViewed 1.4k times

I see my effect fire twice on mount. Is something wrong with my code, or is this expected behavior in React 18?

asked 5 days agoPriya Nair6,386

2 Answers

✓
✓ Accepted answer
React 18 StrictMode intentionally double-invokes effects in development to surface missing cleanup. Your code is fine — production mounts once.
MW
answered 5 days agoMarcus Webb7,334
It only happens in dev — production mounts once. Make sure your effects clean up after themselves and you can ignore the double fire.
SA
answered 4 days agoSofia Alvarez5,306