JAVASCRIPT - Change div class to Active once clicked or Deactive if clicked again

JAVASCRIPT - Change div class to Active once clicked or Deactive if
clicked again

When I click my link the div changes to active and ajax is loaded. But how
can I then say if the link is clicked again that it should become
deactive?
favourite.onclick = function() {
loadXMLDoc('indexFavourite');
favourite.className = 'statusOptionActive';
}