How to access the focus/hover/visited CSS properti

问题:

I may be tired and thinking oddly right now, but I simply cannot find how to retrieve the values of CSS properties defined in an element's focused, hovered or visited states. The goal is to use the values in Javascript.

Important: I do not need to get the focused/hovered/visited elements. I want to access certain values of any element in the DOM with CSS properties defined for the following states: :focus, :hover and :visited.

These pseudo-classes do not seem to help in this case, so do I need to trigger the respective state in order to access the values?

It should be simpler than this... Or is it not?

P.S.: Answers in vegetarian Javascript or jQuery will do.

回答1:

Yes you can achieve this by reading style sheets. You can get it by using document.styleSheets; Below is the example and jsfiddle link.

http://jsfiddle.net/wt3qQ/

For security reasons, Opera and Mozilla will not allow you to access the cssRules collection of a stylesheet from another domain or protocol. Attempting to access it will throw a security violation error

function getStyleBySelector( selector )
   {
       var sheetList = document.styleSheets;
       var ruleList;
       var i, j;

       /* look through stylesheets in reverse order that
          they appear in the document */
       for (i=sheetList.length-1; i >= 0; i--)
       {
           ruleList = sheetList[i].cssRules;
           for (j=0; j<ruleList.length; j++)
           {
               if (ruleList[j].type == CSSRule.STYLE_RULE && 
                   ruleList[j].selectorText == selector)
               {
                   return ruleList[j].style;
               }   
           }
       }
       return null;
   }

console.log(getStyleBySelector('a:hover').color);
console.log(getStyleBySelector('#link:hover').color);