Can't display json result after ajax request on Mamp System

Question

I installed Mamp to work locally on my website. But something strange happened. I have normal return on json (the firebug console display it) but the console log display "undefined" (!)

So firebug display my ajax request and json return :

POST http://local/test.php 200 OK 7ms
{"testjson":"ok"}

But console log display : undefined An idea ?

I checked and json 1.2 is right enabled on Mamp.

test.html :

<script type='text/javascript'>
$(document).ready(function(){
$.ajax({                                            
        type: "POST",
        url: "mod/test.php",
        data: "action=display",
        success: function(response)
        {
                console.log(response['testjson']);
         }  
    });
});

</script>

test.php :

if($_POST['action']=="display")
{
   $response['testjson'] = "ok";
   header('Content-type: application/json');
   echo json_encode($reponse);
   exit;
}

Answer 1

Please remove the below line and try:

header('Content-type: application/json');

Or try one of these following variants:

$.ajax({                                            
  type: "POST",
  url: "mod/test.php",
  data: "action=display",
  success: function(response) {
    console.log(response.testjson);
  }  
});

$.ajax({                                            
  type: "POST",
  url: "mod/test.php",
  data: "action=display",
  success: function(response) {
    response = JSON.parse(response);
    console.log(response['testjson']);
  }  
});

$.ajax({                                            
  type: "POST",
  url: "mod/test.php",
  data: "action=display",
  success: function(response) {
    response = JSON.parse(response);
    console.log(response.testjson);
  }  
});