Bug 241493

Summary: Flashing when observed element is reparented in IntersectionObserver callback (without scroll anchoring)
Product: WebKit Reporter: Mike Taylor <miketaylr>
Component: DOMAssignee: Nobody <webkit-unassigned>
Status: NEW    
Severity: Normal CC: fred.wang, rbuis, simon.fraser, webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: Safari Technology Preview   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
Testcase none

Mike Taylor
Reported 2022-06-09 16:06:42 PDT
(sorry, bad title) This was originally filed against the IntersectionObserver spec: https://github.com/w3c/IntersectionObserver/issues/472 STR: 1. go to https://jsfiddle.net/90sw7dhf/ 2. scroll down Expected: in Firefox and Chrome, alternating green and blue divs, infinitely Actual: in Safari TP, green turns blue, then a different shade of blue and that's it. The jsfiddle has a log, and it seems like it's looping forever when trying to log "wow".
Attachments
Testcase (1.69 KB, text/html)
2022-06-17 20:23 PDT, Simon Fraser (smfr) 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Radar WebKit Bug Importer
Comment 1 2022-06-13 10:48:43 PDT
<rdar://problem/95038984>
Simon Fraser (smfr)
Comment 2 2022-06-17 20:23:32 PDT
Created attachment 460325 [details] Testcase
Simon Fraser (smfr)
Comment 3 2022-06-17 20:26:17 PDT
In both Chrome and Firefox there's a scroll position jump that happens when the elements are moved around. That might be a side effect of scroll anchoring, which Safari doesn't have. Something similar happens in Firefox if I disable scroll anchoring, and that makes sense; moving the elements changes their intersection, which fires the callbacks, which changes the content.
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