问如何判断我的XML是否被正确地解析为JSON？

EN

<html>
<head>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
    <script src="jquery.xml2json.js"></script>
        </head>
    <body>
       <script type="text/javascript">
          $(document).ready(function(){
             $.ajax({
             type:"GET",
             url:"lou.xml",
             datatype:"xml",
             success: function(xml) {
            $.get('lou.xml',function(xml) {
                   var json=$.xml2json(xml);
                   alert(json.message); 
                     });
             }
              })
            });
      </script> 
    </body> 
</html>