https://paducahky.gov/core/misc/announce.js?v=1.33.2

1/**
2 * Adds an HTML element and method to trigger audio UAs to read system messages.
3 *
4 * Use Backdrop.announce() to indicate to screen reader users that an element on
5 * the page has changed state. For instance, if clicking a link loads 10 more
6 * items into a list, one might announce the change like this.
7 * $('#search-list')
8 *   .on('itemInsert', function (event, data) {
9 *     // Insert the new items.
10 *     $(data.container.el).append(data.items.el);
11 *     // Announce the change to the page contents.
12 *     Backdrop.announce(Backdrop.t('@count items added to @container',
13 *       {'@count': data.items.length, '@container': data.container.title}
14 *     ));
15 *   });
16 */
17(function (Backdrop) {
18  var liveElement;
19  var announcements = [];
20  Backdrop.behaviors.backdropAnnounce = {
21    attach: function attach(context) {
22      if (!liveElement) {
23        liveElement = document.createElement('div');
24        liveElement.id = 'backdrop-live-announce';
25        liveElement.className = 'element-invisible';
26        liveElement.setAttribute('aria-live', 'polite');
27        liveElement.setAttribute('aria-busy', 'false');
28        document.body.appendChild(liveElement);
29      }
30    }
31  };
32
33  function announce() {
34    var text = [];
35    var priority = 'polite';
36    var announcement;
37    var il = announcements.length;
38
39    for (var i = 0; i < il; i++) {
40      announcement = announcements.pop();
41      text.unshift(announcement.text);
42
43      if (announcement.priority === 'assertive') {
44        priority = 'assertive';
45      }
46    }
47
48    if (text.length) {
49      liveElement.innerHTML = '';
50      liveElement.setAttribute('aria-busy', 'true');
51      liveElement.setAttribute('aria-live', priority);
52      liveElement.innerHTML = text.join('\n');
53      liveElement.setAttribute('aria-busy', 'false');
54    }
55  }
56
57  /**
58   * Triggers audio UAs to read the supplied text.
59   *
60   * The aria-live region will only read the text that currently populates its
61   * text node. Replacing text quickly in rapid calls to announce results in
62   * only the text from the most recent call to Backdrop.announce() being
63   * read. By wrapping the call to announce in a debounce function, we allow for
64   * time for multiple calls to Backdrop.announce() to queue up their
65   * messages. These messages are then joined and append to the aria-live region
66   * as one text node.
67   *
68   * @param string text
69   *   A string to be read by the UA.
70   * @param string priority
71   *   A string to indicate the priority of the message. Can be either
72   *   'polite' or 'assertive'.
73   *
74   * @return function
75   *   The return of the call to debounce.
76   *
77   * @see http://www.w3.org/WAI/PF/aria-practices/#liveprops
78   * @since 1.18.2 Method added.
79   */
80    Backdrop.announce = function (text, priority) {
81    announcements.push({
82      text: text,
83      priority: priority
84    });
85    return Backdrop.debounce(announce, 300)();
86  };
87})(Backdrop);