I don't know much about browser-side javascript, but unless they're doing something really weird in the event loop I believe the comments

    // this might execute before the $.get() above is complete

and

    // something additional to execute upon success, which might, or might not,
    // have fired by now.  With $.ajax deferreds built-in, it doesn't matter.

are misleading. In fact, the first comment should read "this will execute before the $.get() above is complete" and the second one should read "which will not have fired yet".

Someone please correct me if I'm wrong on this.