827642 - CSS parser rearranges selector text into canonical format

Status: RESOLVED INVALID

(Core :: CSS Parsing and Computation, defect)

Description

[Frank Yan (:fryn)]

I discovered while debugging a patch for bug 821859 that the CSS parser rearranges selector text into its own preferred canonical format and then returns this for the selectorText property of the CSSRule interface.

This can lead to unexpected failures when trying to loop through style sheets to match rules by selector text.

Is this behavior intended?

Comment 1

[Frank Yan (:fryn)]

For example,
a:not([c])[b]
becomes
a[b]:not([c])

Comment 2

[Boris Zbarsky [:bzbarsky]]

This happens with any object model.  The DOM does similar things.

So insofar as there's an object model involved, yes this is intended.  We don't store the text; we store an object with some fields; when you ask for .cssText we serialize the object.

Comment 3

[Frank Yan (:fryn)]

(In reply to Boris Zbarsky (:bz) from comment #2)
> This happens with any object model.  The DOM does similar things.

Good point. That makes sense. Thanks for the concise explanation. :)