JSON object properties are undefined
Either put:
header("Content-type: application/jason");in the PHP, specify dataType: "json" in the AJAX call in the JavaScript, or call JSON.parse.
You will need to parse your string to get a proper JSON object. JSON.parse(response); will provide you with a JSON object from which you can read the properties
Can you try the following example in jsfiddle.
This is not the better way you can use JSON.parse(); or $.parseJSON(); (jquery version)
But if this is your problem, json being returned as a string this fix it and you can alter your code