Javascript alert from JSON response

Question

I'm trying to build an app that gets data from server with getJSON and then alerts the row. This is the code I use but it doesn't show the row from JSON, it just says "undefined". What could be the reason for this?

$(document).ready(function(){

  $("button").click(function(){
    $.getJSON("MyURL/test.php",function(result){
      $.each(result, function(i, field){
        alert(field.MESSAGE);
      });
    });
  });
});

This is the JSON response:

{"key":[{"message":"test"}]}

Answer 1

result isn't an array. result.key is an array. Also your field's property is message, not MESSAGE:

$.each(result.key, function(i, field){
    alert(field.message);
});