https://www.unamur.be/modules/contrib/better_exposed_filters/js/better_exposed_filters.js?v=4.x

1/**
2 * @file
3 * better_exposed_filters.js
4 *
5 * Provides some client-side functionality for the Better Exposed Filters module.
6 */
7
8(function ($, Drupal, drupalSettings) {
9  Drupal.behaviors.betterExposedFilters = {
10    attach: function (context, settings) {
11      // Add highlight class to checked checkboxes for better theming.
12      $('.bef-tree input[type=checkbox], .bef-checkboxes input[type=checkbox]')
13        // Highlight newly selected checkboxes.
14        .change(function () {
15          _bef_highlight(this, context);
16        })
17        .filter(':checked').closest('.form-item', context).addClass('highlight');
18    }
19  };
20
21  /*
22   * Helper functions
23   */
24
25  /**
26   * Adds/Removes the highlight class from the form-item div as appropriate.
27   */
28  function _bef_highlight(elem, context) {
29    $elem = $(elem, context);
30    $elem.attr('checked')
31      ? $elem.closest('.form-item', context).addClass('highlight')
32      : $elem.closest('.form-item', context).removeClass('highlight');
33  }
34
35})(jQuery, Drupal, drupalSettings);