https://chord.co.uk/wp-content/themes/chord/assets/js/modules/sticky-nav.js?ver=7.1.2

1// Sticky element for navs
2//
3// --------------------------------------------------
4function navStickyElement() {
5
6    // Define jQuery (Wordpress uses no conflict)
7    var $ = jQuery;
8
9    var $window = $(window),
10        $body = $('body'),
11        $target = $('.js-sticky-nav'),
12        media_list = matchMedia(helpers().screen_width.sm),
13
14        // State classes
15        state = {
16            sticky: 's-sticky-nav'
17        };
18
19    $target.each(function (){
20
21        var $el = $(this),
22            el_pos = $el.offset().top;
23
24        $window.on('scroll resize', function() {
25
26            if(media_list.matches == true) {
27
28                var window_pos = $window.scrollTop();
29
30                // If the window has passed the position of the element
31                if(window_pos > el_pos) {
32
33                    $body.addClass(state.sticky);
34
35                } else {
36                    if($body.hasClass(state.sticky)) {
37                        $body.removeClass(state.sticky);
38                    }
39                }
40            }
41        });
42    });
43}
44
45jQuery(document).ready( function() {
46
47    var $ = jQuery;
48
49    // Update positions
50    helpers().debounceEvent($(window), 'resize', navStickyElement, 100);
51
52    navStickyElement();
53
54});