if (!document.getElementsByClassName)
{
  document.getElementsByClassName = function(cl)
  {
    var retnode = [];
    var myclass = new RegExp('\\b'+cl+'\\b');
    var elem = this.getElementsByTagName('*');
    for (var i = 0; i < elem.length; i++)
    {
      var classes = elem[i].className;
      if (myclass.test(classes)) retnode.push(elem[i]);
    }
    return retnode;
  };
}