So I have a plugin that creates some images like a gallery. I add it to the page with shortcode:

add_shortcode('foo', 'foo_add_gallery');

I would like to create an option so that the gallery can be previewed in the wordpress admin area. I have managed to make it work like so:

1.

Normally I add my gallery scripts and styles to the frontend with

add_action('wp_enqueue_scripts', 'foo_enqueue_scripts');

Now I need to add them to the backend as well if I want to view the gallery, so I need to run

add_action('admin_enqueue_scripts', 'foo_admin_enqueue_scripts');

(This is where scripts and styles for plugin admin are already added, and I need to add my frontend script and styles in here as well)

2.

I run ajax when I want to preview the gallery and in there I call the same function shortcode would call:

var postData = [
        {name: 'action', value: 'foo_show_gallery_backend'},
        {name: 'gallery_id', value: gallery_id}
    ];

    $.ajax({
        url: foo_data.ajax_url,
        type: 'post',
        data: postData,
        dataType: 'json',   
    }).done(function(response){
        console.log( response)

        $('#some-div').html(response)

    }).fail(function(jqXHR, textStatus, errorThrown) {
        console.log(jqXHR, textStatus, errorThrown);
    });  


add_action('wp_ajax_foo_show_gallery_backend', 'foo_show_gallery_backend');

function foo_show_gallery_backend(){

   $data = foo_add_gallery($atts);

   echo json_encode($data);

   wp_die();

}

(My foo_add_gallery function creates some html and javascript and adds this to the page)

Then I add this response to the page in admin area in a div.