Mutation events

Hi all,

I tested mutation events a bit.

                             | Gecko trunk | WebKit trunk | Opera 10a
DOMAttrModified             |      X      |      -       |     X
DOMCharacterDataModified    |      X      |      X       |     X
DOMNodeInserted             |      X      |      X       |     X
DOMNodeInsertedIntoDocument |      -      |      X       |     X
DOMNodeRemoved              |      X      |      X       |     X
DOMNodeRemovedFromDocument  |      -      |      X       |     X
DOMSubtreeModified          |      X      |      X       |     -


Whenever mutation listeners are used, the relevant DOM operations slow
down a lot in all browser engines. The slow down is up to 10-20x.




I also discussed with some ARIA folks and asked whether it would make
sense to have ARIAAttrModified event (it should be defined in some
ARIA spec). Currently WAI-ARIA best practices[1] recommends using
DOMAttrModified.
IMHO it is a bit strange to utilize mutation events when external AT
software wants to notify a web page that it changed something.
It works, sure, but some ARIA specific API or event might be better.



-Olli

[1] http://www.w3.org/WAI/PF/aria-practices/#aria-write