JSON variable returning correct but value is undefined?

Here is my success function for my ajax request via jquery,

success: function(response) {

    if (response.error == undefined) {

    alert(response);开发者_运维知识库
    }
$('#' + id).after('<div id="emailMsg" class="error">' + response.error + '</div>');

}

Because the value is coming back as undefined it alerts me the returned JSON which is...

{"error":true}

Why is this happening, surely when I call response.error I should get either true or false.

UPDATE

Variable is returning as a string and not boolean, my json_encode();

    if (!$q -> rowCount()) {

    echo json_encode(array('error' => false));
}
else {

    echo json_encode(array('error' => true));
}

You might want to try adding the dataType: 'json' parameter to your $.ajax call. That will ensure that jQuery will take care of making the response an object for you.

You need to first parse the JSON from a string into a JavaScript object.

This can be done with JSON.parse(response). In old browsers that don't have native JSON, eval(response) works too, but is less secure.