> I want a fallback to the request in case the script is run not by url > but with open file from the browser, so i need to know if the request > is working or not
Without questioning the need to handle errors from Request in general, I think you should trap the fact that you're running from the file system as early as possible, set a flag, and just short-circuit before you even try the AJAX calls. Check `location.protocol` (just shorter than what Steve said). Another reason to do it this way is you ensure that you won't confusingly have a mixture of working and non-working AJAX... say you have some absolute URLs or some mashed-up requests to 3rd-party servers, which would otherwise work unless you force everything local. --Sandy
