This questions is bit specific to joomla.
I have created the custom error page error.php in /template/MY_TEMPLATE/error.php. This file checks for the error codes and displays different message for each http code I set(I check with $this->error->code == '404'). Normally this works good.
Now the question is, how should I handle same thing when I am using ajax? When I do an ajax call if an error occurs, I would get http status code back, and the response is the error.php file output. When I get error I would like to redirect the user to the error.php (custom error page) with proper error codes, which would display the messages accordingly!