← Your fetch in beforeunload is silently killed. navigator.sendBeacon guarantees delivery.Quiz
navigator.sendBeacon — reliable analytics on page unload
navigator.sendBeacon sends a POST the browser guarantees to deliver even after the page unloads. These questions cover the API shape, why fetch fails in beforeunload, payload types, the visibilitychange trick, and browser support.
questions9
pass mark70%
resultsat the end
No account needed. Answer all 9 questions, then see your score with every answer explained and a reference to the spec or MDN — pass and you can claim a certificate.