[css-cascade][cssom] Used value of non-applying properties?

• From: Tab Atkins Jr. <jackalmage@gmail.com>
• Date: Mon, 14 Apr 2014 14:26:43 -0700
• To: www-style list <www-style@w3.org>
• Message-ID: <CAAWBYDCeCafB7uEMQVULn3bh2GaXe_BknR9Aw2jA=wqQVBf67g@mail.gmail.com>

The Cascade spec says that if a property doesnt' apply to a given
element, it doesn't have a used value for that property.
<http://dev.w3.org/csswg/css-cascade/#used-value>

However, the used value of some properties (or rather, the
serialziation of the used value) is observable in some ways, such as
getComputedStyle() and the future .usedStyle attribute.  What should
be returned by these?  In particular, what should be returned for
width/height/border/padding/margin used values?

CSSOM currently defines that if the property applies to the element,
the resolved value is the used value; otherwise it's the computed
value.  This gets around the issue, and fits with what Cascade says.
However, only WebKit/Blink do this.  FF and IE appear to return the
layout'd size of the element for width/height, at least.

Should we keep the spec as it is (matching Chrome/Safari), or adjust
it to something special (matching FF/IE)?

~TJ

Received on Monday, 14 April 2014 21:27:30 UTC