how to check if request is ajax in laravel code example

Example: laravel check request is ajax

/**       
         * Display a listing of the resource.
         *
         * @param  Illuminate\Http\Request $request
         * @return Response
         */
        public function index(Request $request)
        {
            if($request->ajax()){
                return "AJAX";
            }
            return "HTTP";
        }