请问如何获取js文件参数???

var d  = document.getElementsByTagName('script');
alert(d[d.length - 1].src.split('?')[1])
或者给script标签设置个id，然后document.getElementById更好。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<script src="a.js?url=www.jj.com" id="s"></script>
    <title>无标题页</title>
</head>
<body>

  <script type="text/javascript">
function queryString(key,url)
{
    var regex_str = "^.+\\?.*?\\b"+ key +"=(.*?)(?:(?=&)|$|#)"
    var regex = new RegExp(regex_str,"i");
    //var url = window.location.toString();
    if(regex.test(url)) return RegExp.$1;
    return undefined;
}

  var s = document.getElementById("s");
  var url = queryString("url",s.src);
  alert(url)

  </script>

</body>
</html>

请问如何获取js文件 参数???