var rollover_image_name = function(origSrc) {
  var splits = origSrc.split('.');
  var extension = splits[splits.length - 1];
  var newSrc = origSrc.replace("." + extension ,"R." + extension + "#hover");
  return newSrc;
}
jQuery(document).ready(function(){
  jQuery.each(jQuery(".rollover"), function(index, el) {
    var origSrc = jQuery(el).attr('src');
    if (origSrc.indexOf("R.") != -1) {
      // it's already rolled over / downstate
      jQuery(el).removeClass('rollover');
    } else {
      // pre-load its rollover image
      var i = new Image;
      i.src = rollover_image_name(origSrc);
    }
  });
  jQuery(".rollover").hover(
    function(){
      var origSrc = jQuery(this).attr("src");
      newSrc = rollover_image_name(origSrc);
      jQuery(this).attr("src",newSrc);
    },
    function(){
      var origSrc = jQuery(this).attr("src");
      var splits = origSrc.split('.');
      var extension_pre = splits[splits.length - 1];
      var extension = extension_pre.split('#')[0];
      var oldSrc = jQuery(this).attr("src").replace("R." + extension + "#hover","." + extension);
      jQuery(this).attr("src",oldSrc);
    }
  );
});