AJAX Requests — CodeIgniter 4.1.4 documentation
AJAX Requests. The IncomingRequest::isAJAX () method uses the X-Requested-With header to define whether the request is XHR or normal. However, the most recent JavaScript implementations (i.e., fetch) no longer send this header along with the request, thus the use of IncomingRequest::isAJAX () becomes less reliable, because without this header ...