[jQuery] Catching 401 errors to $.ajax calls

[Christoph Haas]

Fellow earthicans,

I would like to use $.ajaxSetup to set up a global error handler that
knows how to deal with HTTP 401 codes ("Authentication required"). I
am enhancing a few tables with AJAX using jQuery but I made my backend
send back an HTTP error code 401 to force authentication if the user's
login session timed out. The idea was to redirect to the '/login' page
then.

This is what I tried:

        $.ajaxSetup({
            error: function (XMLHttpRequest, textStatus, errorThrown)
{
                alert(errorThrown + '/' + textStatus + '/' +
XMLHttpRequest)
            }
        })

Unfortunately the errorThrown is "undefined" and textStatus just
contains "error". Of course I can just redirect to /login on any error
but that's not what I want.

When I tried ExtJS for my project (I've dumped that meanwhile and went
back to jQuery - don't worry) I was successful with this code:

    Ext.Ajax.on({
        requestexception: function(conn, response, options, e)
        {
            if (response.status == '401')
                window.location.href = '/login';
        }
    });

Can anyone tell me how to properly catch 401 requests globally with
jQuery?

Kindly
 Christoph