In theory the correct way to send analytics when leaving the page is via navigator.sendBeacon, although it's not clear how reliable it is: https://volument.com/

In theory the correct way to send analytics when leaving the page is via navigator.sendBeacon, although it's not clear how reliable it is: https://volument.com/blog/sendbeacon-is-broken https://volument.com/blog/sendbeacon-is-broken (note: read the comments for some rebuttals to the article)