function ChangeLinksClass(){
        for (var i=0; i<document.links.length; i++){
          Link=document.links[i].pathname;
          HaveExtension=Link.lastIndexOf('.');
          if (HaveExtension >= 0){
            Extension=Link.substring(HaveExtension+1);
            Class=Extension + '_link';
            document.links[i].className = Class;
          }
        }
      }
      window.onload = function() {
         ChangeLinksClass();
      }