https://www.ksutab.org/modules/contrib/dismiss/js/dismiss.js?v=10.6.8

1/**
2 * @file
3 * Main JavaScript file for Dismiss module.
4 */
5
6(function ($, Drupal) {
7  /**
8   * Add the dismiss icon to the message list.
9   */
10  Drupal.behaviors.dismiss = {
11    attach(context, settings) {
12      // Prepend the Dismiss button to each message box.
13      $('.messages').each(function () {
14        const flag = $(this).children().hasClass('dismiss');
15        if (!flag) {
16          $(this).prepend(
17            '<button class="dismiss"><span class="element-invisible"></span></button>',
18          );
19        }
20      });
21      // When the Dismiss button is clicked hide this set of messages.
22      $('.dismiss').click(function (event) {
23        $(this).parent().hide('fast');
24        // In case this message is inside a form, prevent form submission.
25        event.preventDefault();
26      });
27    },
28  };
29})(jQuery, Drupal);