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HTML

CSS

CSS Base

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JavaScript

Babel includes JSX processing.

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HTML

              
                <div id="redBox">
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Sit corporis dolorum sapiente cupiditate. Dolorum ut facilis, odit nihil itaque ipsa alias reiciendis quae, aperiam libero veniam nesciunt asperiores eos illum!</p>
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Quam pariatur aspernatur maxime beatae magnam tempora alias, temporibus dignissimos quae rerum delectus sint fugit quaerat voluptatum ea eum aliquam. Veritatis, officiis?</p>
</div>
<br><br><br><br><br><br>
<div class="awesomeSauce">
  <h2>Targetted Section</h2>
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Animi magnam architecto aliquid earum dolorem, quibusdam voluptates debitis ipsam saepe repellendus ducimus esse voluptas quis. Error nostrum dolorum magnam expedita animi!</p>
</div>
<div>
  <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Necessitatibus debitis quibusdam voluptas sed. Delectus perferendis natus sunt fugit tempore, vero commodi voluptas minima dolore odit quam enim nulla expedita ad.</p>
</div>


              
            
!

CSS

              
                body {
  font-family:sans-serif;
}

h1 {
  margin: 5px 0;
}
h3 {
  margin:0;
  font-size:16px;
}
.demo {
  width:600px;
  height:120px;
  background-color:black;
  position:relative;
}

.box {
  width:50px;
  height:50px;
  position:relative;
  margin-bottom:2px;
}

.red {
  background-color:red;
}

.blue {
  background-color:blue;
}

.green {
  top:60px;
  left:25px;
  background-color:green;
}

.nav {
  width:600px;
  background-color:#ccc;
  text-align:right;
}

button {
  padding:10px;
  font-size:20px;
}

div{
  padding: 1em 0;
}


              
            
!

JS

              
                //***********
//setting up rAF, code from HTML5rocks
//***********
var rAF = requestAnimationFrame || mozRequestAnimationFrame || webkitRequestAnimationFrame || msRequestAnimationFrame;

//debouncing animation from trigger event and triggering only when scroll happens
var latestKnownScrollY = 0,
  ticking = false;

function onScroll() {
  latestKnownScrollY = window.scrollY;
  requestTick();
}

function requestTick() {
  if (!ticking) {
    rAF(update);
  }
  ticking = true;
}

function update() {
  // reset the tick so we can
  // capture the next onScroll
  ticking = false;
  var currentScrollY = latestKnownScrollY;

  //read window inner height property to determine appear location
  var windowHeight = window.innerHeight;
  var scrollAppearLocation = (windowHeight * 6 / 9) + currentScrollY;

  // read offset of DOM elements
  // and compare to the currentScrollY value
  // then apply some CSS classes // to the visible items

  if ($(".awesomeSauce").length) {
    addAnimationClass("awesomeSauce");
  }

  function addAnimationClass(targetName) {
    var targetObject = document.getElementsByClassName(targetName)[0];
    var targetObjectOffsetTop = targetObject.offsetTop;

    //debug positioning
    console.log('scrollAppearLocation = ' + scrollAppearLocation);
    console.log('targetObjectOffsetTop = ' + targetObjectOffsetTop);

    var tween = new TweenMax('.' + targetName, '3', {
      opacity: 0,
    });
    //mimic tween from behavior
     tween.pause();

    if (scrollAppearLocation > targetObjectOffsetTop) {
      //allow element to appear
      tween.reverse();
      tween.resume();
    } else {
      //hide element
      tween.restart();
      // tween.reverse();
      // tween.pause;
    }
  }

}

window.addEventListener('scroll', onScroll, false);
              
            
!
999px

Console