On Thu, Sep 24, 2009 at 12:02 AM, Mike Wilson <[email protected]> wrote:
> Yes, the base for event delegation is certainly something
> like that. I just wanted to make clear that the main reason
> for adding this functionality (IMO) is event delegation.
> I'll let event delegation library creators chime in on the
> details on what is needed for making really efficient
> behavioural/delegation implementations, and judge the merits
> of various optimizations. There has f ex already been mention
> of caching "parsed" selectors.
>
The benefit to that is that the selector text is parsed once, so
something like:-
document.onmouseover = function(ev) {
if(ev.target.matchesSelector(".infotip")) { /*...*/ }
};
could probably be made more efficient as:-
var selector = QuerySelector.create(".infotip");
document.onmouseover = function(ev) {
if(selector.matches(ev.target)) { /*...*/ }
};
The type of context where a QuerySelector object would be useful are
described above. That could be abstracted to a factory pattern that
uses selector to match nodes in a delegated event and lazily construct
a wrapper.
QuerySelector could be extended to have properties:
readonly attribute boolean valid
StaticNodeList match(in HTMLElement contextNode)
Garrett
