Fix navigace a butonu

by Petr Haluza

HTML

<body>
    <div class="home">
<header id="masthead" class="site-header" role="banner">
		<div class="site-branding">
		<h1 class="site-title"><a href="#" rel="home">tEST</a></h1>
		<p class="site-description">yyyy</p>
		<button class="secondary-toggle" style="display: none;">xxxx</button>
		</div><!-- .site-branding -->
	</header>
    
     <header class="yahoo">
        <h1>Yahoo</h1>
         <button id='yourButton'>THIS BUTTON</button>
    </header>
        
        <p>
            Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
        </p>
        
        <p>
            Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
        </p>
        
        <p>
            Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
        </p>
        
        <p>
            Lorem ipsum dolor sit amet,...

CSS

.yes p {    background: coral!important;}
button {    display: none;}
button.active {    display: block;}
.yahoo {    width: 100%;
    position: fixed;
    top: 0;
    transform: translateY(20%);
    visibility: hidden;
    opacity: 0;
    transition: all 0.3s;}
.yes .yahoo { visibility: visible; transform: translateY(0); opacity: 1;
  /* top: 0; */
}
.yes .site-header { display: block;}

JavaScript

var lastScrollY     = 0,
        ticking         = false;

function onScroll() {
    lastScrollY = window.scrollY;
    requestTick();
}
function requestTick() {
    if(!ticking) {
        requestAnimFrame(update);
        ticking = true;
    }
}
function update() {
    var bbody = document.querySelector('body');
    var btn = document.getElementById('yourButton');
    
        
    if(lastScrollY > 50) {
        bbody.classList.add('yes');
        console.log('yes');
    } else {
        bbody.classList.remove('yes');
        console.log('no');
    }
    
    if(lastScrollY > 150) {
        btn.classList.add('active');
    }
    else {
        btn.classList.remove('active');
    }
    
    
    // allow further rAFs to be called
    ticking = false;
}


window.addEventListener('scroll', onScroll, false);

// shim layer with setTimeout fallback
window.requestAnimFrame = (function(){
    return  window.requestAnimationFrame       ||
        window.webkitRequestAnimationFrame ||
        window.mozRequestAnimationFrame    ||
        window.oRequestAnimationFrame      ||
        window.msRequestAnimationFrame     ||
        function( callback ){
            window.setTimeout(callback, 1000 / 60);
        };
})();