Retrieve a property defined in a css

[Nicolas Terray <nicolas.terray (at) gmail.com>]

On 2/16/06, Nicolas Terray <nicolas.terray (at) gmail.com> wrote:
> Hi all,
>
> I have a property, defined in an external stylesheet:
>
> .my_class {
>    background-color: #FF0000;
> }
>
>
> I want to retrieve the value of this background-color of the class my_class.
>
> How can I do that with prototype/scriptaculous ?
>
> Thanks in advance,
> Nicolas Terray
>

I've just found this script:
---8<---------
function getStyleClass (className) {
  var re = new RegExp("\\." + className + "$", "gi");
  if (document.all) {
    for (var s = 0; s < document.styleSheets.length; s++)
      for (var r = 0; r < document.styleSheets[s].rules.length; r++)
        if (document.styleSheets[s].rules[r].selectorText.search(re)
!= -1) {
          return document.styleSheets[s].rules[r].style;
        }
  }
  else if (document.getElementById) {
    for (var s = 0; s < document.styleSheets.length; s++)
      for (var r = 0; r < document.styleSheets[s].cssRules.length; r++)
        if (document.styleSheets[s].cssRules[r].selectorText.search
(re) != -1) {
          document.styleSheets[s].cssRules[r].sheetIndex = s;
          document.styleSheets[s].cssRules[r].ruleIndex = s;
          return document.styleSheets[s].cssRules[r].style;
        }
  }
  else if (document.layers)
    return document.classes[className].all;
  return null;
}
function getStyleClassProperty (className, propertyName) {
  var styleClass = getStyleClass(className);
  if (styleClass)
    return styleClass[propertyName];
  else
    return null;
}
---8<---------
http://www.faqts.com/knowledge_base/view.phtml/aid/1939/fid/255

It works pretty find on Fx 1.0.7 and IE6 however I don't understand
all in this script.
What does those lines mean :
          document.styleSheets[s].cssRules[r].sheetIndex = s;
          document.styleSheets[s].cssRules[r].ruleIndex = s;
???

As javascript experts, could you tell me if this script is correct,
not too old and unoptimizable ?

Anyways, other suggestions are welcome!

Thanks,
Nicolas Terray
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