window.addEvent("domready",function(){
  observe_forms();
});

function observe_forms(){
  $$('form').each(function(form){
  form.removeEvents();
  var cart = $('cart');
  form.set('send', {
    method: 'post',
      onRequest: function(){
        add_spinner(cart);
      },
      onComplete: function(response){
        cart.setHTML(response);
        observe_forms();
     }
  });
  form.addEvent('submit', function(evt){
     evt.stop();
     form.send();
  });
});
};

function add_spinner(target){
  var spinner = new Element('img',{'src':'/images/spinner.gif','class':'spinner'});
  spinner.injectInside(target);
};