https://nasen.org.uk/modules/custom/nsg_membership/js/registration_form.js?tlu6x5

1(function ($, Drupal) {
2  Drupal.behaviors.toggleRegistrationFieldset = {
3    attach: function (context) {
4      $(once('registrationTogglerClicker', '.fieldset-toggler', context)).click(function (event) {
5        event.preventDefault();
6        let $id = '#' + $(this).attr('data-toggle-id');
7        $(this).addClass('d-none');
8        $($id).removeClass('d-none');
9        $($id)[0].scrollIntoView({
10          behavior: 'smooth',
11          block: 'center'
12        });
13      });
14    },
15  };
16  Drupal.behaviors.membershipChosen = {
17    attach: function (context) {
18      $(once('membershipChosen', '.choose-membership-toggler', context)).click(function (event) {
19        event.preventDefault();
20        let $id = $(this).data('id');
21        $('[data-drupal-selector="edit-membership-chosen"]').val($id);
22        $('.membership-card').each(function (ke, el) {
23          $(this).addClass('inactive');
24        })
25        $(this).closest('.membership-card').removeClass('inactive');
26        $(this).closest('.choose-membership').find('.fieldset-toggler').trigger('click');
27      });
28
29      // $(once('membershipActive', '.membership-card', context)).each(function (key, element) {
30      //   let $active = $('[data-drupal-selector="edit-membership-chosen"]').val();
31      //   let $id = $(this).data('article-id');
32      //   $(this).removeClass('active ');
33      //   if (parseInt($id) === parseInt($active) && $active !== 0) {
34      //     $(this).addClass('active');
35      //   }
36      // });
37    },
38  }
39})(jQuery, Drupal);