Hide header on scroll down, show on scroll up

by ian_smithz

HTML

<header>
    <h1>LOGO</h1>
</header>
<ul class="mainmenu">
    <li>Home</li>
    <li>Menu</li>
    <li>Blog</li>
    <li>Privacy</li>
    <li>Contact</li>
</ul>
<main>
    This is your body.
</main>
<footer>
    This is your footer.
</footer>

CSS

body {
    padding-top: 40px;
}
header{ height:100px; text-align:center;}
h1{color:#222;font-size: 45px;}

/* Sticky */
.mainmenu {
    background: #222;
    height: 200px;
    padding: 0 15px;
    width: 100%;
    margin: 0 auto;
}
.nav-down{
    position: fixed;
    top: 0;
    transition: top 0.2s ease-in-out;
    width: 100%;
}
.nav-up {
    top: -200px;
}

.mainmenu{text-align: center;}
.mainmenu li{display: inline-block; color: #fff;font-size: 12px; line-height: 50px;text-transform: uppercase;margin-right:10px;}


main {
    height: 2000px;
}

footer { background: #222;}
* { color: transparent}

JavaScript

$(window).bind('scroll', function () {
    
    if ($(window).scrollTop() > 150)
        $('.mainmenu').addClass('nav-down');
    else
        $('.mainmenu').removeClass('nav-down');
});


// Hide Header on on scroll down
var lastScrollTop = 0;
var delta = 5;
var navbarHeight = $('.mainmenu').outerHeight();

$(window).scroll(function(event){
    
    var st = $(this).scrollTop();
    
    // Make sure they scroll more than delta
    if(Math.abs(lastScrollTop - st) <= delta)
        return;
    
    // If they scrolled down and are past the navbar, add class .nav-up.
    // This is necessary so you never see what is "behind" the navbar.
    if (st > lastScrollTop && st > navbarHeight){
        // Scroll Down
        $('.mainmenu').removeClass('nav-down').addClass('nav-up');
    } else {
        // Scroll Up
        if(st + $(window).height() < $(document).height()) {
            $('.mainmenu').removeClass('nav-up');
        }
    }
    
    lastScrollTop = st;
});