Adding JS to Drupal 8 Theme with .once()

my_theme.info.yml

name: My Theme
type: theme
base theme: adminimal_theme
description: 'Admin theme, sub-theme of Adminimal'
core: 8.x

libraries:
- my_theme/theme_base

my_theme.js

(function ($) {
  Drupal.behaviors.my_theme= {
    attach: function (context, settings) {

      // create a toggle to show hidden display:none content
      $('#selector-id', context).once('my_theme').click(function () {
        $('.hidden-object--show').slideToggle();
        $(this).toggleClass('active');
      });

      // without an interactive toggle, show the hidden content
      if (!$('#selector-id').length > 0) {
        $('.hidden-object--show').show();
      }
    }
  };
})(jQuery);

my_theme.libraries.yml

theme_base:
  version: VERSION
  js:
    my_theme.js: {}
  dependencies:
  - core/jquery