Re: AnimationEvents for pseudo-elements

On Fri, Feb 1, 2013 at 2:12 PM, Boris Zbarsky <bzbarsky@mit.edu> wrote:

> On 2/1/13 2:04 PM, Tab Atkins Jr. wrote:
>
>> On Fri, Feb 1, 2013 at 9:10 AM, Boris Zbarsky <bzbarsky@mit.edu> wrote:
>>
>>> On 2/1/13 11:31 AM, Alexis Menard wrote:
>>>
>>>> Is the pseudoElement attribute what you are looking for?
>>>>
>>>
>>> Is that actually compatible with existing content?  In particular, this
>>> will
>>> trigger existing event listeners that didn't use to be triggered
>>> before...
>>>
>>
>> In WebKit it definitely won't, because transitions and animations only
>> very recently started working on pseudos anyway.  ^_^
>>
>
> ...
>
>  I'd prefer avoiding a rename just for this if we can.
>>
>
> In case it wasn't clear, my proposal is that we have transitionend for
> normal transitions and something like beforetransitionend for transitions
> on ::before, say.
>
>
That doesn't scale, then we need beforetransitionend and
aftertransitionend, and firstlettertransitionend,
and webkitinnerspinbuttontransitionend, ...

Supporting this is important for Shadow DOM
because input::-webkit-inner-spin-button is really just
my-widget::internal-pseudo-element and you want to know when your internal
pseudos have finished animating. Inside the ShadowRoot the
::internal-pseudo-element is just a <div>, but when it crosses the boundary
it should retarget to the myWidget and pseudoElement should become
"internal-pseudo-element". The alternative would be to not retarget the
event, but to refire a whole new event with a different name which we don't
have any existing cases that I'm aware of.

I suppose if we had to go that route it'd be okay, but Dimitri would need
to comment. It seems really unfortunate to add that kind of behavior though.

Separately I've received personal email from developers expressing that
they want this to just fire the regular events. We did actually fire them
on the internal PseudoElement when I first landed support, and someone even
asked me to leave that in because it was useful. :)

- E