drupal-vue/docroot/themes/custom/vue_js/dist/js/modal-non-vue.js

!function (document, Drupal, $) {
  'use strict';

  Drupal.behaviors.drupalVueModal = {
    attach: function attach(context) {

      $('#non-vue-modal-button', context).on('click', function (e) {
        e.preventDefault();
        $('#non-vue-modal .modal__mask').removeClass('hidden');
      });

      $('#non-vue-modal .modal__close', context).on('click', function (e) {
        e.preventDefault();
        $('#non-vue-modal .modal__mask').addClass('hidden');
      });
    }
  };
}(document, Drupal, jQuery);