Event.addBehavior({
  '#filter:change' : function() {
		var params = this.serialize() + "&authenticy_token=6971c34c65fe24c265a0368d9254db827da4060b";
	  new Ajax.Request('/admin/orders', {
			asynchronus:true, 
			evalScripts:true, 
			method:'get', 
			parameters: params
		});
	}
});

Event.addBehavior({
	'#filter_on_this:change' : function() {
		if (this.value == "created_at") {
			$('created_at').show();
			$('delivery_date').hide();
		} else {
			$('created_at').hide();
			$('delivery_date').show();
		}
	}
});