The ordering of the cues in TextTrack is defined as follows: > ... cues must be sorted by their start time, earliest first; then, any cues with the same start time must be sorted by their end time, latest first; and finally, any cues with identical end times must be sorted in the order they were last added ... > https://html.spec.whatwg.org/multipage/media.html#text-track-cue-order However, there is a current issue where mutating a property of a TextTracCue/VTTCue (expect for .startTime/.endTime) results in a rearrangement of cues, causing cues with identical start/end time to be resorted, then deviating from the intended order. The same issue in Chromium: https://bugs.chromium.org/p/chromium/issues/detail?id=783779
Pull request: https://github.com/WebKit/WebKit/pull/18488
Committed 268857@main (1e25aac1511a): <https://commits.webkit.org/268857@main> Reviewed commits have been landed. Closing PR #18488 and removing active labels.
<rdar://problem/116475605>