Json communication from php to jquery

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Jquery code: 

$.post(url",{'product[]':b,store_id:slave_stores[d]}, function (data){

                  var response = $.parseJSON(data);

                  if(typeof(response.count) != 'undefined') {

                               alert( response.count);
                   }

});
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Php Code in ajax function:

$reply = array(

                    'count' => $pcount,

                      'message' => "testing"

);

echo json_encode($reply);