Re: [webcomponents] Need "slotting changed" event (#288)

@hayatoito in WebKit, such a check can be done in O(k) where k is the number of slots each node has to go through during distribution assuming the slots within each shadow tree have not been mutated (no slot was removed or inserted).

Having said that, I like async event best.  Neither mutation observer nor an event at end-of-microtask makes much sense given the use cases presented thus far are all about updating the appearance, which doesn't need to occur until right before the browser paints the page.  There is no need to keep adding useless records or keep firing at the end of each micro-task.

---
Reply to this email directly or view it on GitHub:
https://github.com/w3c/webcomponents/issues/288#issuecomment-186101511