Looking through the source, I see that the "textStatus" parameter of
$.ajax's error callback can be one of the following values:
* timeout - when your specified timeout is exceeded
* error - http error, like 404
* notmodified - when requested resource was not modified since
last request
* parsererror - when an xml/json response is bad
I would like it if this was in the documentation for $.ajax and
$.ajaxError - I didn't realize those statuses were being provided by
jQuery, and I don't think I could have found out about them without
reading the source.
