https://reveillerlesliens.fr/themes/margot/javascripts/hide-navbar-on-scroll.js?v=4.6.7

1// Hide Header on on scroll down
2var didScroll;
3var lastScrollTop = 0;
4var scrolldelta = 5;
5var body = $('body');
6var ywnavbar = $('#yw-topnav');
7var navbarHeight = ywnavbar.outerHeight();
8var minOffsetForHiding = 300;
9
10$(window).scroll(function (event) {
11  didScroll = true;
12});
13
14setInterval(function () {
15  if (didScroll) {
16    hasScrolled();
17    didScroll = false;
18  }
19}, 250);
20
21function hasScrolled() {
22  var st = $(this).scrollTop();
23  // Make sure they scroll more than delta
24  if (Math.abs(lastScrollTop - st) <= scrolldelta)
25    return;
26
27  // If they scrolled down and are past the navbar, add class .nav - up.
28  // This is necessary so you never see what is "behind" the navbar.
29  if (st > lastScrollTop && st > navbarHeight && ywnavbar.hasClass('fixable') && st > minOffsetForHiding) {
30    // Scroll Down
31    ywnavbar.addClass('nav-up');
32    body.addClass('nav-up');
33    ywnavbar.removeClass('nav-down');
34    body.removeClass('nav-down');
35  } else {
36    // Scroll Up
37    if (st + $(window).height() < $(document).height()) {
38      ywnavbar.addClass('nav-down');
39      body.addClass('nav-down');
40      ywnavbar.removeClass('nav-up');
41      body.removeClass('nav-up');
42    }
43  }
44
45  lastScrollTop = st;
46}