[Webkit-unassigned] [Bug 219038] New: Load event fires multiple times

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=219038

            Bug ID: 219038
           Summary: Load event fires multiple times
           Product: WebKit
           Version: Safari 14
          Hardware: Unspecified
                OS: Unspecified
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: Page Loading
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: milan.keser at dynatrace.com
                CC: beidson at apple.com

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.

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