Re: Path to polyfilling CSS functions?

On Mon, Aug 6, 2012 at 3:16 PM, L. David Baron <dbaron@dbaron.org> wrote:

> On Monday 2012-08-06 15:02 -0700, Boris Smus wrote:
> > Writing polyfills for this should be easy, right? Well, not really. It
> used
> > to be the case the the CSS object model would retain unknown CSS rules as
> > UnknownRules. However, this changed in 2003 as a result of this email
> [2].
> > As far as I know, there has been an attempt to get UnknownRule back into
> > the spec [3], through a CSS Editing Task Force, but nothing ever came of
> > this.
>
> The issue you're concerned about is retaining unknown declarations
> within style rules, not retaining unknown rules.
>

Exactly right, thanks for the correction.


> I think if what you were interested in were supporting unknown
> properties, it would be useful to have an API like the ones described
> in:
> https://bugzilla.mozilla.org/show_bug.cgi?id=188321#c14
> https://www.w3.org/Bugs/Public/show_bug.cgi?id=14203


Marat's proposal in the above bug seems fine, but why not just extend the
existing CSS OM via document.styleSheets[i].cssRules[j].style[k]? If the
CSS parser added unknown properties to the tree there, it would be easy to
traverse (in JS) the CSS rules and declaration tree, polyfilling as you
went.


> Unknown values of existing properties would be a bit harder.
>
> > It would be great if UnknownRule was still available, since it'd allow us
>
> I think characterizing this as "still available" is misleading.
> There was an entirely fictional specification that briefly described
> a feature without making any serious attempt to explain how it
> should work.  I don't think it was ever implemented.


> -David
>
> --
> 𝄞   L. David Baron                         http://dbaron.org/   𝄂
> 𝄢   Mozilla                           http://www.mozilla.org/   𝄂
>