https://museum-id.com/wp-content/themes/headway/library/blocks/navigation/js/selectnav.js?ver=7.1.2

1/**
2 * @preserve SelectNav.js (v. 0.1)
3 * Converts your <ul>/<ol> navigation into a dropdown list for small screens
4 * https://github.com/lukaszfiszer/selectnav.js
5 */
6
7window.selectnav = (function(){
8
9"use strict";
10
11  var selectnav = function(element,options){
12
13  	if ( typeof element == 'string' )
14   		element = document.getElementById(element);
15
16    // return immediately if element doesn't exist
17    if( ! element){
18      return;
19    }
20
21    // return immediately if element is not a list
22    if( ! islist(element) ){
23      return;
24    }
25
26    // return immediately if no support for insertAdjacentHTML (Firefox 7 and under)
27    if( ! ('insertAdjacentHTML' in window.document.documentElement) ){
28      return;
29    }
30
31    // add a js class to <html> tag
32    document.documentElement.className += " js";
33
34    // retreive options and set defaults
35    var o = options || {},
36
37      activeclass = o.activeclass || 'active',
38      autoselect = typeof(o.autoselect) === "boolean" ? o.autoselect : true,
39      nested = typeof(o.nested) === "boolean" ? o.nested : true,
40      indent = o.indent || "→",
41      label = o.label || "- Navigation -",
42
43      // helper variables
44      level = 0,
45      selected = " selected ";
46
47    // insert the freshly created dropdown navigation after the existing navigation
48    element.insertAdjacentHTML('afterend', parselist(element) );
49
50    var nav = document.getElementById(id());
51
52    // autoforward on click
53    if (nav.addEventListener) {
54      nav.addEventListener('change',goTo);
55    }
56    if (nav.attachEvent) {
57      nav.attachEvent('onchange', goTo);
58    }
59
60    return nav;
61
62    function goTo(e){
63
64      // Crossbrowser issues - http://www.quirksmode.org/js/events_properties.html
65      var targ;
66      if (!e) e = window.event;
67      if (e.target) targ = e.target;
68      else if (e.srcElement) targ = e.srcElement;
69      if (targ.nodeType === 3) // defeat Safari bug
70        targ = targ.parentNode; 
71
72      if(targ.value) window.location.href = targ.value; 
73    }
74
75    function islist(list){
76      var n = list.nodeName.toLowerCase();
77      return (n === 'ul' || n === 'ol');
78    }
79
80    function id(nextId){
81      for(var j=1; document.getElementById('selectnav'+j);j++);
82      return (nextId) ? 'selectnav'+j : 'selectnav'+(j-1);
83    }
84
85    function parselist(list){
86
87      // go one level down
88      level++;
89
90      var length = list.children.length,
91        html = '',
92        prefix = '',
93        k = level-1
94        ;
95
96      // return immediately if has no children
97      if (!length) {
98        return;
99      }
100
101      if(k) {
102        while(k--){
103          prefix += indent;
104        }
105        prefix += " ";
106      }
107
108      for(var i=0; i < length; i++){
109
110        var link = list.children[i].children[0];
111        if(typeof(link) !== 'undefined'){
112          var linkToGetText = jQuery(link);
113          	linkToGetText.find('.sf-sub-indicator').remove();
114
115          var text = linkToGetText.text();
116          var isselected = '';
117
118          if(activeclass){
119            isselected = link.className.search(activeclass) !== -1 || link.parentNode.className.search(activeclass) !== -1 ? selected : '';
120          }
121
122          if(autoselect && !isselected){
123            isselected = link.href === document.URL ? selected : '';
124          }
125
126          html += '<option value="' + link.href + '" ' + isselected + '>' + prefix + text +'</option>';
127
128          if(nested){
129            var subElement = list.children[i].children[1];
130            if( subElement && islist(subElement) ){
131              html += parselist(subElement);
132            }
133          }
134        }
135      }
136
137      // adds label
138      if(level === 1 && label) {
139        html = '<option value="">' + label + '</option>' + html;
140      }
141
142      // add <select> tag to the top level of the list
143      if(level === 1) {
144        html = '<select class="selectnav" id="'+id(true)+'">' + html + '</select>';
145      }
146
147      // go 1 level up
148      level--;
149
150      return html;
151    }
152
153  };
154
155  return function (element,options) {
156    selectnav(element,options);
157  };
158
159
160})();