JS 根据参数名称得到地址栏的参数

<script type="text/javascript">
  function hooyesQueryString(queryStringName)
{
 var returnValue="";
 var URLString=new String(document.location);
 var serachLocation=-1;
 var queryStringLength=queryStringName.length;
 do { serachLocation=URLString.indexOf(queryStringName+"\=");
  if (serachLocation!=-1)
  {
   if ((URLString.charAt(serachLocation-1)=='?') || (URLString.charAt(serachLocation-1)=='&'))
   {
    URLString=URLString.substr(serachLocation); break;
    }
    URLString=URLString.substr(serachLocation+queryStringLength+1);
    } 
    } while (serachLocation!=-1) if (serachLocation!=-1)
    {
     var seperatorLocation=URLString.indexOf("&");
     if (seperatorLocation==-1)
     {
       returnValue=URLString.substr(queryStringLength+1);
       }
       else
        {
          returnValue=URLString.substring(queryStringLength+1,seperatorLocation);
          }
           }
           alert(returnValue);        

           }
   </script>