[jQuery] jQuery.ajax() not calling beforeSend?

[jQuery] jQuery.ajax() not calling beforeSend?


I need to set some headers (I wish this were doable by just passing in
a map), but it seems that beforeSend is never being called. Needless
to say that's a bit of a problem for me.
The alert below never occurs (and a breakpoint is never hit if I put
it there), but I can see that the ajax request is being sent.
        j$.ajax({
            'url': serviceUrl,
            dataType: "jsonp",
            data: params,
            beforeSend: function(req) {
alert("inside!");
}
        });