https://quedlinburg.de/layout/_premium/assets/js/focus-within.js?__ts=1572856312

1/**
2 * :focus-within Polyfill
3 * @return {boolean}
4 */
5function polyfill() {
6  var CLASS_NAME = 'focus-within';
7  var WHITE_SPACE = ['\n', '\t', ' ', '\r'];
8
9  /**
10   * Calculate the entire event path.
11   *
12   * @param {Element} node
13   * @return {Array} computedPath
14   */
15  function computeEventPath(node) {
16    var path = [];
17    var parent = null;
18
19    while ((parent = node.parentNode || node.host || node.defaultView)) {
20      path.push(parent);
21      node = parent;
22    }
23
24    return path;
25  }
26
27  /**
28   * Add user defined attribute to element retaining any previously
29   * applied attributes. Attribute can be the 'class' attribute for
30   * compatibility reasons.
31   *
32   * @param {string} value
33   * @return {function(Element)} callback
34   */
35  function addClass(value) {
36    return function(el) {
37      var attributes = (el && typeof el.getAttribute !== 'undefined') ?
38        el.getAttribute('class') || '' :
39        undefined;
40
41      if (typeof attributes !== 'undefined' &&
42        attributes.indexOf(value) === -1) {
43        el.setAttribute('class', attributes.concat(' ', value).trim());
44      }
45    };
46  }
47
48  /**
49   * Remove user defined attribute value or entire attribute if last one.
50   * Attribute can be the 'class' attribute for compatibility reasons.
51   *
52   * @param {string} value
53   * @return {function(Element)} callback
54   */
55  function removeClass(value) {
56    return function(el) {
57      var attributes = (el && typeof el.getAttribute !== 'undefined') ?
58        el.getAttribute('class') || '' :
59        undefined;
60
61      if (attributes) {
62        var index = attributes.indexOf(value);
63        // Check if `value` exists in `attributes` and it is either
64        // at the start or after a whitespace character. This stops
65        // "focus-within" being remove from "js-focus-within".
66        if (index >= 0 &&
67            (index === 0 ||
68              WHITE_SPACE.indexOf(attributes.charAt(index - 1)) >= 0)) {
69          var newAttributes = attributes.replace(value, '').trim();
70          (newAttributes === '') ?
71            el.removeAttribute('class') :
72            el.setAttribute('class', newAttributes);
73        }
74      }
75    };
76  }
77
78  /**
79   * Attach event listerns to initiate polyfill
80   * @return {boolean}
81   */
82  function load() {
83    var handler = function(e) {
84      var running;
85
86      /**
87       * Request animation frame callback.
88       * Remove previously applied attributes.
89       * Add new attributes.
90       */
91      function action() {
92        running = false;
93
94        if ('blur' === e.type) {
95          Array.prototype.slice
96              .call(computeEventPath(e.target))
97              .forEach(removeClass(CLASS_NAME));
98        }
99
100        if ('focus' === e.type) {
101          Array.prototype.slice
102              .call(computeEventPath(e.target))
103              .forEach(addClass(CLASS_NAME));
104        }
105      }
106
107      if (!running) {
108        window.requestAnimationFrame(action);
109        running = true;
110      }
111    };
112
113    document.addEventListener('focus', handler, true);
114    document.addEventListener('blur', handler, true);
115    addClass('js-focus-within')(document.body);
116    return true;
117  }
118
119  try {
120    return !document.querySelector(':' + CLASS_NAME);
121  } catch (error) {
122    return load();
123  }
124}
125
126polyfill();