How to get value of my custom gallery setting and display it on frontend

Hi with this snippet i created additional fields to gallery settings:

[ Moderator note: code fixed. Please wrap code in the backtick character or use the code button. ]

<script type="text/html" id="tmpl-slideshow-gallery-settings">
    <label class="setting">
      <span><?php _e('Display'); ?></span>
      <select data-setting="slideshow_attr">
        <option value="default"> Default gallery </option>
        <option value="zzlslideshow"> Slideshow </option>
        <option value="masonry"> Masonry gallery </option>
      </select>
    </label>
		<label class="setting">
        <span><?php _e('imgwidth'); ?></span>
        <input type="text" value="" data-setting="imgwidth_text" style="float:left;">
    </label>
		<label class="setting">
        <span><?php _e('imgheight'); ?></span>
        <input type="text" value="" data-setting="imgheight_text" style="float:left;">
    </label>
  </script>

  <script>

    jQuery(document).ready(function(){

      // add your shortcode attribute and its default value to the
      // gallery settings list; $.extend should work as well...
      _.extend(wp.media.gallery.defaults, {
        slideshow_attr: 'zzlslideshow'
      });

      // merge default gallery settings template with yours
      wp.media.view.Settings.Gallery = wp.media.view.Settings.Gallery.extend({
        template: function(view){
          return wp.media.template('gallery-settings')(view)
               + wp.media.template('slideshow-gallery-settings')(view);
        }
      });

    });

  </script>

But now i could use some help. How can i get the chosen values and display them on frontend. For example: if option: zzlslidehow is chosen i want in frontend flexslider2 displayed. Can anyone tell me how to do so