Hi,
I'm planning to look at beginning work on Selectors API v2 soon to
add a number of requested features that didn't make it into the first
version. This e-mail is a summary of what is being considered, and is
intended to start discussion about which ones are really worth focussing
on, and how to ensure they address the use cases appropriately.
*Matches Selector*
http://www.w3.org/Bugs/Public/show_bug.cgi?id=5865
The suggestion is for being able to check if a given element matches a
given selector. There is already similar functionality provided by
JQuery and Mozilla have begun working on an implementation for it in
Firefox.
For the basic case, this is fairly trivial. The method just needs to
take a selector and evaluate it against the element, and return true or
false.
But considering the proposed :scope pseudo-class that has been
previously discussed here and in the CSS WG, it might also be nice to
check if the element matches the selector in relation to a specified
reference element.
For example, given 2 elements, div1 and div2, you could check if div2 is
a sibling of div1 like this:
div2.matchesSelector(":scope~div", div1);
In this case, the div1 would be the reference element that is matched by
:scope. But we still need to determine how useful such functionality
would be, and whether it's worth pursuing it in this next version.
*Filtering NodeLists*
http://www.w3.org/Bugs/Public/show_bug.cgi?id=5864
The suggestion is for being able to take a NodeList, and filter the
nodes to obtain a collection of just those that match a given selector.
For example, being able to get a NodeList somehow, do something with it,
and then filter it more to work with just a subset:
e.g.
var list = document.querySelctor("div>p");
// Do something with list, before obtaining the subset
subset = list.filterSelector(".foo");
...
We need to find and document the possible use cases for this feature.
*Scoped Queries*
http://www.w3.org/Bugs/Public/show_bug.cgi?id=5860
This has been discussed extensively in the past. Basically, the idea is
that the selector would be evaluated in the scope of the element, in a
way more compatible with how libraries like JQuery work. This slightly
different from the :scope pseudo-class proposal, see bug for details.
*Collective Queries on NodeLists*
http://www.w3.org/Bugs/Public/show_bug.cgi?id=7707
The suggestion is to be able to run querySelector() and
querySelectorAll() on NodeList, and have the result be the union of
results in document order from running the method on each Element in the
NodeList.
e.g.
list.querySelectorAll("p");
Would be somewhat equivalent to running list[i].querySelectorAll("p");
for on each element in the list, and then building an array with the
union of distinct elements from all the results. I've been told that
similar functionality for this already exists in JQuery.
I believe the expectation is that both NodeList.querySelector() and
.querySelectorAll() would work. The difference is that querySelector()
on a NodeList would return a NodeList (unlike on Element which just
returns a single element) containing the first matches from each node in
the list. i.e. equivalent to running list[i].querySelector() on each
node and then combining all results into an array.
It also seems sensible to allow the new scoped methods to be used in an
analogous way on NodeLists.
*Namespace Prefix Resolution*
http://www.w3.org/Bugs/Public/show_bug.cgi?id=6290
The most controversial issue of the lot. Need to clearly document the
use cases and evaluate the problems being solved, and determine if it's
really worth addressing in this version.
--
Lachlan Hunt - Opera Software
http://lachy.id.au/
http://www.opera.com/
