For some reason we get duplicate load events in Safari 14 and 13 when we redirect the page during the onload event. userAgent = Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0 Safari/605.1.15 How to reproduce: Create an html page Add onload listener to body element In onload listener click the button Click on button changes the location.href and goes to another page What we do: We have a tracking tool that is injected as the first script in head tag. We register load listener and create a beacon with metrics when load fires. For some reason beacon sending fails if we redirect in onload event listener that is added to body element. We get "failed to get a response" response from that beacon sending. However that beacon somehow gets to the server with duplicate load event data. This only happens on Safari 13 and 14, we are running this also on safari 12 and all other major browsers and we do not see this issue.
Other possibility is that the failed beacon sending was trying to be resend multiple times from browser, but we cannot really be sure since browser shows only one request in console
Thanks for filing, if possible please link to a live test case.
<rdar://problem/71546102>