Unload event listeners are deprecated and will be removed

[teusbenschop]

window.addEventListener ("unload", resourceUnload);

The unload event listener is being deprecated and removed by major browsers.

These handlers, often used for analytics or cleanup, break the back/forward cache (bfcache), causing slower performance and poor user experience.

Developers should replace unload with pagehide or visibilitychange events for better performance and reliability.