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Re: [selectors4] Use pesudo-class instead for selecting parent elems

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 3 Sep 2013 08:15:00 -0700
Message-ID: <CAAWBYDAdUtetDNUPqLhiYswzhX+sRJGmA-AtnJ0NYv-3c5XyAQ@mail.gmail.com>
To: Simon Sapin <simon.sapin@exyr.org>
Cc: Xidorn Quan <quanxunzhen@gmail.com>, www-style list <www-style@w3.org>
On Tue, Sep 3, 2013 at 1:24 AM, Simon Sapin <simon.sapin@exyr.org> wrote:
> Le 03/09/2013 09:15, Simon Sapin a écrit :
>> Le 03/09/2013 03:00, Xidorn Quan a écrit :
>>> I believe that :matches which supports complete complex selector is
>>> hard, if not impossible, to be implemented in a fast way, but it is
>>> possible for the pseudo-class I requested which narrows the looking-up
>>> range to its descendents.
>>
>> Is it? As far as I understand, the problem here is that a dynamic change
>> anywhere in the tree, in the presence of such selectors, would require a
>> big part of the tree or the whole document to be restyled.
>>
>> Does your proposal really help with that? Especially (see below) if the
>> argument to :has() can start with a combinator.

Boris has said before that a restricted form of :has() that only
selected for children would likely be acceptable from a performance
standpoint.

> I should add: I’m not convinced that :has() solves any performance problem,
> but if it turns out to be equivalent in expressive power to the subject
> indicator, I like this proposed syntax better. (:has() has no equivalent to
> multiple subject indicators in the same selector, but I’m not overly
> attached to that feature.)

It's equivalent, yes.  Depending on what you're doing, it may be more
or less convenient to express a given selector.

~TJ
Received on Tuesday, 3 September 2013 15:15:50 UTC

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