PHP JQuery Json

PHP:

echo Json_encode($result);

Jquery:

$.get(
                'process.php',
                {'p1':'aa','p2':'dd', 'data_type':'json'},
                function(data){                        
                    var resultJson=jQuery.parseJSON(data);
                    if(resultJson.length>0)
                        alert(resultJson[0][AA];
                        alert(resultJson.A.AA);                
                }
      );