1 Commits (0f458d5abaafaeaaeb15009700e6f7747c8f4121)

Author	SHA1	Message	Date
Khaled Waleed	955b701df2	fix: measure nested transitions before applying their starting styles (#18647) ... Fixes #18421 (regression from #16035, which re-broke the #4784 scenario). Since #16035 the dummy delay animation runs with `fill: 'forwards'`, so an intro's `t = 0` styles (for `slide`, `height: 0`) apply the moment the transition is created and stay applied until the real animation starts a frame later. Transition functions of other elements in the same batch run after that and measure a collapsed DOM. With nested intros (the TreeView from the issue), intro effects run deepest-first, so every ancestor's `slide` captures a height where its children are pinned at 0. On the issue's REPL every `<ul>` animates `0px -> 36px` (the height of a single row) and then jumps to its real size when the animation finishes, which is the "children pop out" behavior from #4784. The fix waits one microtask before applying the initial styles and creating the dummy, the same way deferred transitions (`crossfade`) already work in `animate()`. Everything in the batch measures the DOM first; the microtask still runs before the next paint, so elements never render unstyled and the #14732 behavior is preserved. Verified in a real browser that a delayed intro (`delay: 300`) stays held at `height: 0` for the whole delay, including the first painted frame. Most of the diff is the existing dummy/onfinish block moving into `queue_micro_task`; hiding whitespace shows the actual change.	4 days ago