JQuery AJAX return function as data on success

I have a codeigniter flashdata + jQuery AJAX call to show it. code:

<script type="application/javascript">

var res_no = '<?php echo $this->session->flashdata('res_no'); ?>';
var res_new = '<?php echo $this->session->flashdata('res_new'); ?>';

(function( $ ) {

$("#check-reservations").click(function() {

   $.ajax({
            type: "POST",
            url: "mycontroller/function",
            async: true,
            data: {
            res_no: res_no,
            res_new: res_new
            },
            success: function(data) {   
            if(data) {
            alert(data);
            }
           }
        });
     });

/*
Default Notifications
*/
$('#check-reservations').show(function() {

    if (res_no) {
    new PNotify({
        title: 'Hmm no new Reservations..',
        text: res_no,
        type: 'custom',
        addclass: 'notification-primary',
        icon: 'fa fa-info-circle '
    });
    }

    else if (res_new) {
    new PNotify({
        title: 'There\ something new!',
        text: res_new,
        type: 'custom',
        addclass: 'notification-success',
        icon: 'fa fa-check'
    });
    }
   });
   }).apply( this, [ jQuery ]);
 </script>

      

        
        
        
      

    

inside the $ .ajax data, I added both

res_no: res_no,
res_new: res_new

      

        
        
        
      

    

which are just lines of text, upon success I return back a warning with text. I want to come back

new PNotify({
        title: 'Hmm no new Reservations..',
        text: res_no,
        type: 'custom',
        addclass: 'notification-primary',
        icon: 'fa fa-info-circle '
    });

      

        
        
        
      

    

PHP:

 /**
    * @filtered_reservations
    * @index
    */
    $filtered_reservations = $this->filter_array($reservations);          
    if (count($filtered_reservations) > 0) {
    foreach ($filtered_reservations as $index => $reservation) {
    $this->db->insert('reservations', $reservation);   
    } // end foreach   
    return $this->session->set_flashdata('res_new', "Success ". count($filtered_reservations) ." Reservations were Inserted!"); 
    print "Success ". count($filtered_reservations) ." Reservations were Inserted!";
    print "Reservations: ". count($kigores_id) ." found on kigo!";
    } /* end if */


    /**
    * @filtered_reservations
    * equal to 0
    */
    elseif (count($filtered_reservations) === 0) {
    print "Sorry no new Reservations!";
    return $this->session->set_flashdata('res_no', 'Sorry no new Reservations!');
    //$this->ci_alerts->set('warning', "Sorry no new Reservations!");
    }

    } /* end reservations */     

      

        
        
        
      

    

What should I write in the data? The only solution I have found so far is window.reload which will show me a notification the way I want but with an update.