I’m trying to find an answer to this, but the web has been remarkably unforthcoming. This includes the usually stellar Stack Overflow. Here’s what’s going on:

* I’ve gotten comfortable in jQuery over the past few months. It is awesome.
* I’ve just started playing with XMLHttpRequest objects (i.e.,“Ajax”).
* jQuery has a few methods to help you do XMLHttpRequest calls, e.g., .get() and the lower-level .ajax().
* If a .get() request succeeds, you can attach a success callback to it. The arguments handed to the callback include the XMLHttpRequest object itself.
* XMLHttpRequest objects, according to the spec, have a getAllResponseHeaders() method.
* It would seem to follow, then, that the XMLHttpRequest object in jQuery.get() and jQuery.ajax() would also contain a getAllResponseHeaders() method. If it does, I can’t get Firebug to print its results; it only tells me “null.” Null is a kind of sadness.
* Other pages, including the Stack Overflow one that I mentioned, indicate that other people have had this same problem. But no one seems to have solved it. So I’m putting the description up here; when I solve it, I will contribute to the world’s stock of knowledge, and a great light will shine forth upon the land. Hosannas, etc.