https://www.kuntaliitto.fi/modules/contrib/better_exposed_filters/js/bef_datepickers.js?tlcg33

1/**
2 * @file
3 * bef_datepickers.js
4 *
5 * Provides jQueryUI Datepicker integration with Better Exposed Filters.
6 */
7
8(function ($, Drupal, drupalSettings) {
9  /*
10   * Helper functions
11   */
12
13  Drupal.behaviors.betterExposedFiltersDatePickers = {
14    attach: function (context, settings) {
15
16      // Check for and initialize datepickers.
17      var befSettings = drupalSettings.better_exposed_filters;
18      if (befSettings && befSettings.datepicker && befSettings.datepicker_options && $.fn.datepicker) {
19        var opt = [];
20        $.each(befSettings.datepicker_options, function (key, val) {
21          if (key && val) {
22            opt[key] = JSON.parse(val);
23          }
24        });
25        $('.bef-datepicker').datepicker(opt);
26      }
27
28    }
29  };
30})(jQuery, Drupal, drupalSettings);