Consider this Django view which will get a list of items associated to the current user:
@login_required
def list_items(request, page_number=0):
items = Pagi
You could use something like http://amplifyjs.com/ that lets you write a nice wrapper for your AJAX calls and then use its data mapping feature to check if the user is still logged in before doing the AJAX call.
This way you can have a client-side timer that sets the user to logged-out status and provides a hint so the login check doesn't need to be done before every AJAX call.
Alternatively you can use a custom decoder which asks the user to log in and retries the AJAX call if the user was logged out. It would need to store all the xhr data and callbacks it gets called with until the user logs in.