better way

JavaScript2/week3/script.js

Line 32 in 5b0e127

callback(data);

here you are parsing the request data and then you callback the render function, so you should pass an object not (theData), try to make it this way:
callback(xmlHttp.responseText);
and inside your callback parse the data into js object and then render your dom.

[JiDarwish]

But why shouldn't I parse it inside the XHR function? I think it would give the same resault