On 20/10/11 8:42 PM, Lachlan Hunt wrote:
On 2011-10-20 10:14, Sean Hogan wrote:
The primary use-case for matchesSelector() has been event-delegation,
and this is the same for matches(). More specifically, consider the
following scenario:
jQuery adds a new event registration method that uses event delegation
to mimic the behavior of:
$(elem).find("> div > .thinger").bind(eventType, fn);
The new method is called proxybind(), and the equivalent of the above
is:
$(elem).proxybind("> div > .thinger", eventType, fn);
The event handling for proxybind() would invoke matches("> div >
.thinger", [elem]) on elements between the event target and elem to find
matching elements.
It may not be too late to introduce that behaviour into
matchesSelector, with a switch based on the presence or absence of the
refNodes/refElement parameter.
As currently specified, calling the following doesn't and shouldn't
prepend :scope.
el.matchesSelector("div .foo");
This one also matches the prefixed implementations in browsers, since
most haven't started supporting :scope yet, and I don't believe
Mozilla's experimental implementation [1] has landed yet.
As currently specified, calling this:
el.matchesSelector("div .foo", ref);
Also doesn't prepend :scope automatically, but in that case, the ref
nodes do nothing useful.
But this selector can still match elements. Admittedly I can't think of
a use-case for this, but it is conceivable for someone to expect this to
work without an implied :scope.
Authors have to use :scope explicitly for them to be useful as in
something like:
el.matchesSelector(":scope div .foo", ref);
Or
el.matchesSelector("div:scope .foo", ref);
One thing we could possibly do is define that if ref nodes are passed,
and the selector doesn't explicitly use :scope, then effectively
prepend ":scope ". This would be exactly the same behaviour as that
discussed for .findAll();
That wouldn't break compatibility with anything, optimises for a
common case and avoids introducing two separate match methods.
I don't see the need for findAll(), but if it is added I think it should
always imply ":scope " at the start of a selector, and I think a
separate match method that does the same should be added. To do
otherwise seems too ambiguous for a DOM API.
e.g.
el.matchesSelector("div .foo"); // No ref, no magic :scope
el.matchesSelector("div .foo", ref); // Implied, magic :scope
el.matchesSelector("+.foo", ref); // Implied, magic :scope
el.matchesSelector(":scope div .foo", ref); // Explicit, no magic :scope
el.matchesSelector("div:scope .foo", ref); // Explicit, no magic :scope
[1] https://bugzilla.mozilla.org/show_bug.cgi?id=648722
