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[selectors-api] comments on Selectors API Level 2

From: Daniel Glazman <daniel.glazman@disruptive-innovations.com>
Date: Wed, 20 Jan 2010 08:50:44 +0100
Message-ID: <4B56B5D4.8070408@disruptive-innovations.com>
To: public-webapps@w3.org
Cc: "www-style@w3.org" <www-style@w3.org>
Hi there.

(this message contains personal comments and does not represent an
  official response from the CSS WG)

I have read the recent Selectors API Level 2 draft [1] and have a few
important comments to make:

1. I don't like the idea of refNodes. I think having the APIs specified
    at Element level makes it confusing. I would recommend applying the
    NodeSelector interface to NodeList instead. If queryScopedSelector()
    and queryScopedSelectorAll() are applied to an Element or a NodeList,
    the corresponding element(s) are the refNodes of the query.
    Same comment for matchesSelector().

2. I am extremely puzzled by the parsing model of scoped selectors. In
    particular, I think that the :scope pseudo-class introduces things
    that go far beyond scoping. Let's consider the selector ":scope+p".
    Clearly, it's _not_ scoped since it queries element that are outside
    of the subtree the context element is the root of. Furthermore, these
    elements can be queried without scopes, and I don't see why this is
    needed at all!!!
    I would recommend dropping the pseudo-class :scope and make a simpler
    model where a fictional :scope pseudo-class and a descendant
    combinator are prepended to all selectors passed as the argument of
    the corresponding APIs.

    I don't like the idea that implementors will have to check if the
    first sequence of simple selectors in a selector contains or does
    not contain a given pseudo-class to prepend something to the context.
    This is clearly the kind of things I think we should avoid in
    Selectors in general.

3. the section about :scope does not include error handling. What
    happens if multiple :scope are present?

4. what's the specificity of that pseudo? Since it's proposed as a
    regular and non-fictional pseudo, web authors _can_ use it in
    regular stylesheets, even if it's meaningless outside of a scoped
    stylesheet. What's the behaviour in that case? What's the

[1] http://www.w3.org/TR/selectors-api2/

W3C CSS WG, Co-chair
Received on Wednesday, 20 January 2010 07:51:17 UTC

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