Ajax loading image gallery WordPress ( coded for oliveorange.com )

Ajax loading image gallery WordPress

/* localize script */
	wp_enqueue_script( 'settings', get_template_directory_uri() . '/js/settings.js', array('jquery'), OO_Version, true );

	wp_localize_script( 'settings', 'localized', array(
        'ajaxurl'       => admin_url( 'admin-ajax.php' )
    ));
    
/* setting.js */
    jQuery(function($){

        var counter = 0;

        function loadGallery() {
            $.ajax({
                type: "POST",
                url: localized.ajaxurl,
                data: ({ action: 'ajax_gallery', counter: counter }),
                beforeSend: function(){
                    $('.gallery').append('<p class="loading">loading...</p>');
                },
                success: function(msg){
                    $('.gallery').append(msg).hide().fadeIn('slow');
                    $('.gallery a').simpleLightbox();
                    $('.gallery').find('.loading').fadeOut('slow');
                }

            });

            counter++;
        }

        loadGallery();

        $('.load-btn a').click(function( e ){   
            e.preventDefault();
            loadGallery();
        }); //event handler 

    });
    
    
   /* shortcode */
function gallery_query_shortcode($atts) {
    $output_string = '<div class="gallery"></div>';
    $output_string .= '<div class="load-btn">
					        <a href="#">Load more</a>
					    </div>';
	return $output_string;
}	
add_shortcode('gallery', 'gallery_query_shortcode');

/* ajax response */
function query_gallery_func($atts) {

/* get gallery items from admin option by piklist */
	$oo_options = get_option('oliveorange_setting');
	$gallery = $oo_options['gallery'];
	
	$counter = $_POST['counter'];
	$organized_arr = array_chunk($gallery, 8);

	/* get number of clicks from ajax */
	$current_loop = $organized_arr[$_POST['counter']];

	if(isset($current_loop)) :
	ob_start();

	?>
     	<?php foreach($current_loop as $k => $v) : ?>
        <a href="<?php echo wp_get_attachment_image_src($v, 'full')[0]; ?>"><img src="<?php echo wp_get_attachment_image_src($v, 'gallery')[0]; ?>" alt="Event Image" title="Event Image" />
        </a>
        <?php endforeach; ?>

		<?php else : ?>
			<p> No more item found! </p>
		<?php endif; ?>

	<?php
	$output_string = ob_get_contents();
	ob_end_clean();
	echo $output_string;
	exit();
}

add_action('wp_ajax_ajax_gallery','query_gallery_func');
add_action('wp_ajax_nopriv_ajax_gallery','query_gallery_func');