function changecss(theClass,element,value)
    {
    //documentation for this script at http://www.shawnolson.net/a/503/
    var cssRules;
    if (document.all)
    {
    cssRules = 'rules';
    }
    else if (document.getElementById)
    {
    cssRules = 'cssRules';
    }
     
    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 == theClass)
    {
    document.styleSheets[S][cssRules][R].style[element] = value;
    }
    }
    }
    }

مثال استفاده:changecss('.exampleA','display','none'); changecss('#exampleB','display','none');