← Your `fetch()` in `beforeunload` is being silently dropped. Use `navigator.sendBeacon()`.Quiz
navigator.sendBeacon() — reliable unload data
navigator.sendBeacon() is the correct API for sending analytics, session-end events, and error reports when a page unloads. These questions check why fetch() fails in beforeunload, what sendBeacon() guarantees, what data types it accepts, how its return value works, why visibilitychange is preferred over beforeunload, and when keepalive fetch is a better fit.
questions8
pass mark70%
resultsat the end
No account needed. Answer all 8 questions, then see your score with every answer explained and a reference to the spec or MDN — pass and you can claim a certificate.