236155 2022-02-04 13:32:41 -0800 PerformanceObserver should work with {type: 'paint', buffered: true } 2022-02-09 10:08:33 -0800 1 1 1 Unclassified WebKit DOM Safari 15 Unspecified Unspecified RESOLVED DUPLICATE 225305 BrowserCompat, InRadar P2 Normal --- 1 andrewscheuermann webkit-unassigned bfulgham noam simon.fraser webkit-bug-importer wilander oldest_to_newest 1837575 0 andrewscheuermann 2022-02-04 13:32:41 -0800 ** Steps to reproduce: ** 1. Navigate to example.com (or any web page) in Safari and run the following code in the console: ``` new PerformanceObserver((list) => { console.log('callback invoked'); list.getEntries().forEach(console.log); }).observe({ type: 'paint', buffered: true }); ``` ** Actual Results: ** Nothing is logged and the callback is not invoked. ** Expected Results: ** A PerformancePaintTiming entry should be logged. The paint entry is logged with this other approach... ``` performance.getEntriesByType('paint').forEach(console.log); ``` ** Additional Information: ** Related Stack Overflow question -> https://stackoverflow.com/questions/70989089/new-performanceobservercb-observe-type-paint-buffered-true-doesnt-w 1837628 1 webkit-bug-importer 2022-02-04 16:14:19 -0800 <rdar://problem/88513217> 1838280 2 simon.fraser 2022-02-07 11:58:01 -0800 *** This bug has been marked as a duplicate of bug 78011 *** 1838963 3 simon.fraser 2022-02-08 16:57:46 -0800 Not a dup. 1839022 4 noam 2022-02-08 22:34:41 -0800 This is already covered in a web platform test: https://wpt.live/paint-timing/fcp-only/fcp-iframe.html From what I checked it works as expected in safari. I also tested it manually in a fresh page. Note that the observer needs to be added before the paint happens - in your example steps that's not the case. Can you post a test page where you add an observer before the paint and the observer is not called? 1839226 5 andrewscheuermann 2022-02-09 09:48:36 -0800 To clarify, the "Steps to reproduce" show a PerformanceObserver that is created with {type: 'paint', buffered: true}. The presence of the buffered parameter means that the PerformanceObserver callback should invoke with paint entries that occurred ~before~ the observer is added. You can reproduce this buffered behavior on Chrome, Firefox, Opera, and Edge by copying in the code at any time after the initial paint occurs. I've updated the bug description to "PerformanceObserver should work with {type: 'paint', buffered: true }" https://developer.mozilla.org/en-US/docs/Web/API/PerformanceObserver/observe#parameters 1839240 6 noam 2022-02-09 09:58:57 -0800 (In reply to Andrew Scheuermann from comment #5) > To clarify, the "Steps to reproduce" show a PerformanceObserver that is > created with {type: 'paint', buffered: true}. The presence of the buffered > parameter means that the PerformanceObserver callback should invoke with > paint entries that occurred ~before~ the observer is added. > > You can reproduce this buffered behavior on Chrome, Firefox, Opera, and Edge > by copying in the code at any time after the initial paint occurs. > > > I've updated the bug description to "PerformanceObserver should work with > {type: 'paint', buffered: true }" > > https://developer.mozilla.org/en-US/docs/Web/API/PerformanceObserver/ > observe#parameters Ah. I think this is a dup of https://bugs.webkit.org/show_bug.cgi?id=225305 1839244 7 noam 2022-02-09 10:05:46 -0800 *** This bug has been marked as a duplicate of bug 225305 *** 1839249 8 noam 2022-02-09 10:08:33 -0800 I marked it as dup, and found an existing failing WPT for this https://wpt.fyi/results/paint-timing/fcp-only/buffered-flag.window.html?label=experimental&label=master&aligned which would make it easier to reproduce and fix.