<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<!------ Include the above in your HEAD tag ---------->
<header>
<div class="logo">STICKY MENU ON SCROLL!</div>
<div class="intro">Some dumbass tagline goes here</div>
<div class="menu">Menu goes here - home - links - blah blah</div>
</header>
<div class="content">
<h2>Dummy content below this line.</h2>
<p>Bacon ipsum dolor sit amet culpa adipisicing andouille ut, salami bresaola spare ribs shank fatback cupidatat est. Occaecat beef flank fatback beef ribs. Sed tempor officia, proident ullamco elit short loin ham hock short ribs laborum pariatur. Nisi frankfurter sint, boudin aute andouille chicken corned beef. Shank pariatur pork loin deserunt et nostrud, sausage ut.</p>
<p>Qui sed elit leberkas enim prosciutto aliqua shank occaecat. Labore enim proident short loin strip steak ut. Bresaola ea sed pariatur culpa sint ham hock tri-tip shoulder. Sed jowl sunt chuck mollit jerky.</p>
<p>Ball tip ham hock pariatur dolore, minim pig qui non filet mignon. Duis dolore do pork belly aute. In consequat mollit consectetur dolore. Short ribs duis tempor, deserunt dolore pastrami pancetta do aliquip jerky sed qui spare ribs tri-tip. Qui jerky culpa eu drumstick chicken sausage brisket.</p>
<p>Bacon ipsum dolor sit amet culpa adipisicing andouille ut, salami bresaola spare ribs shank fatback cupidatat est. Occaecat beef flank fatback beef ribs. Sed tempor officia, proident ullamco elit short loin ham hock short ribs laborum pariatur. Nisi frankfurter sint, boudin aute andouille chicken corned beef. Shank pariatur pork loin deserunt et nostrud, sausage ut.</p>
<p>Qui sed elit leberkas enim prosciutto aliqua shank occaecat. Labore enim proident short loin strip steak ut. Bresaola ea sed pariatur culpa sint ham hock tri-tip shoulder. Sed jowl sunt chuck mollit jerky.</p>
<p>Ball tip ham hock pariatur dolore, minim pig qui non filet mignon. Duis dolore do pork belly aute. In consequat mollit consectetur dolore. Short ribs duis tempor, deserunt dolore pastrami pancetta do aliquip jerky sed qui spare ribs tri-tip. Qui jerky culpa eu drumstick chicken sausage brisket.</p>
<p>Bacon ipsum dolor sit amet culpa adipisicing andouille ut, salami bresaola spare ribs shank fatback cupidatat est. Occaecat beef flank fatback beef ribs. Sed tempor officia, proident ullamco elit short loin ham hock short ribs laborum pariatur. Nisi frankfurter sint, boudin aute andouille chicken corned beef. Shank pariatur pork loin deserunt et nostrud, sausage ut.</p>
<p>Qui sed elit leberkas enim prosciutto aliqua shank occaecat. Labore enim proident short loin strip steak ut. Bresaola ea sed pariatur culpa sint ham hock tri-tip shoulder. Sed jowl sunt chuck mollit jerky.</p>
<p>Ball tip ham hock pariatur dolore, minim pig qui non filet mignon. Duis dolore do pork belly aute. In consequat mollit consectetur dolore. Short ribs duis tempor, deserunt dolore pastrami pancetta do aliquip jerky sed qui spare ribs tri-tip. Qui jerky culpa eu drumstick chicken sausage brisket.</p><p>By creating a clone, we can create <em>another</em> (identical) instance of the menu and make that one always sticky. It will always be there, but depending on the scrolled position, it will (or will not) show. When it shouldn't be visible, we can't have it "overlap" or obscure any other elements, which is why we use show/hide instead of visible/invisible (if it would just be invisible, it would technically block everything under it from user interaction).</p>
<p>SOOOOO, the <strong>original</strong> menu toggles between visible/invisible (to not mess with the positioning of the elements on the rest of the page), while the <strong>cloned</strong> menu toggles between show/hide (to not mess with the elements under it).</p>
<h2>TL;DR</h2>
<p>- Page creates a cloned copy of the menu, which will have the exact same look/feel as the original menu (because it's an identical sibling), but is sticky at the top of the page.<br>- When we DON'T need a sticky menu, the original static menu shows normally and the cloned sticky menu is set to not show.<br>- When we DO need a sticky menu, the original static menu is invisible and the cloned sticky one is set to show.</p>
<h2>Dummy content below this line.</h2>
<p>Bacon ipsum dolor sit amet culpa adipisicing andouille ut, salami bresaola spare ribs shank fatback cupidatat est. Occaecat beef flank fatback beef ribs. Sed tempor officia, proident ullamco elit short loin ham hock short ribs laborum pariatur. Nisi frankfurter sint, boudin aute andouille chicken corned beef. Shank pariatur pork loin deserunt et nostrud, sausage ut.</p>
<p>Qui sed elit leberkas enim prosciutto aliqua shank occaecat. Labore enim proident short loin strip steak ut. Bresaola ea sed pariatur culpa sint ham hock tri-tip shoulder. Sed jowl sunt chuck mollit jerky.</p>
<p>Ball tip ham hock pariatur dolore, minim pig qui non filet mignon. Duis dolore do pork belly aute. In consequat mollit consectetur dolore. Short ribs duis tempor, deserunt dolore pastrami pancetta do aliquip jerky sed qui spare ribs tri-tip. Qui jerky culpa eu drumstick chicken sausage brisket.</p>
<p>Bacon ipsum dolor sit amet culpa adipisicing andouille ut, salami bresaola spare ribs shank fatback cupidatat est. Occaecat beef flank fatback beef ribs. Sed tempor officia, proident ullamco elit short loin ham hock short ribs laborum pariatur. Nisi frankfurter sint, boudin aute andouille chicken corned beef. Shank pariatur pork loin deserunt et nostrud, sausage ut.</p>
<p>Qui sed elit leberkas enim prosciutto aliqua shank occaecat. Labore enim proident short loin strip steak ut. Bresaola ea sed pariatur culpa sint ham hock tri-tip shoulder. Sed jowl sunt chuck mollit jerky.</p>
<p>Ball tip ham hock pariatur dolore, minim pig qui non filet mignon. Duis dolore do pork belly aute. In consequat mollit consectetur dolore. Short ribs duis tempor, deserunt dolore pastrami pancetta do aliquip jerky sed qui spare ribs tri-tip. Qui jerky culpa eu drumstick chicken sausage brisket.</p>
<p>Bacon ipsum dolor sit amet culpa adipisicing andouille ut, salami bresaola spare ribs shank fatback cupidatat est. Occaecat beef flank fatback beef ribs. Sed tempor officia, proident ullamco elit short loin ham hock short ribs laborum pariatur. Nisi frankfurter sint, boudin aute andouille chicken corned beef. Shank pariatur pork loin deserunt et nostrud, sausage ut.</p>
<p>Qui sed elit leberkas enim prosciutto aliqua shank occaecat. Labore enim proident short loin strip steak ut. Bresaola ea sed pariatur culpa sint ham hock tri-tip shoulder. Sed jowl sunt chuck mollit jerky.</p>
<p>Ball tip ham hock pariatur dolore, minim pig qui non filet mignon. Duis dolore do pork belly aute. In consequat mollit consectetur dolore. Short ribs duis tempor, deserunt dolore pastrami pancetta do aliquip jerky sed qui spare ribs tri-tip. Qui jerky culpa eu drumstick chicken sausage brisket.</p>
</div>
.menu {
width: 100%;
background: yellow;
}
// Create clone of menu, right next to original.
$('.menu').addClass('original').clone().insertAfter('.menu').addClass('cloned').css('position','fixed').css('top','0').css('margin-top','0').css('z-index','500').removeClass('original').hide();
scrollIntervalID = setInterval(stickIt, 10);
function stickIt() {
var orgElementPos = $('.original').offset();
orgElementTop = orgElementPos.top;
if ($(window).scrollTop() >= (orgElementTop)) {
// scrolled past the original position; now only show the cloned, sticky element.
// Cloned element should always have same left position and width as original element.
orgElement = $('.original');
coordsOrgElement = orgElement.offset();
leftOrgElement = coordsOrgElement.left;
widthOrgElement = orgElement.css('width');
$('.cloned').css('left',leftOrgElement+'px').css('top',0).css('width',widthOrgElement).show();
$('.original').css('visibility','hidden');
} else {
// not scrolled past the menu; only show the original menu.
$('.cloned').hide();
$('.original').css('visibility','visible');
}
}
