js 给url添加时间戳

js 给url添加时间戳 骗过浏览器缓存

 function convertURL(url){
   var timstamp = (new date).valueOf();
   if (url.indexOf("?")>=0){
      url = url + "&t=" + timstamp;
   }else {
      url = url + "?t=" + timstamp;
   };
   return url;
 };