JSFiddle - React, Tailwind, and code Playground

by funkwurm

HTML

<div id="body">
    <div id="sectionA" class="div">First section</div>
    <div id="sectionB" class="div">Second section</div>
    <div id="sectionC" class="div">Third section
        <div class="box"></div>
        <div class="box"></div>
        <div class="box"></div>
    </div>
    <div id="footer" class="div cf">Footer</div>
</div>

CSS

* {
    margin: 0;
    padding: 0
}
body {
    background-color: #800000
}

/* clear fix */
cf:after {
    visibility:hidden;
    display:block;
    content:"";
    clear:both;
    height:0
}
* html .cf {
    zoom:1
}
/* IE6 */
 *:first-child+html .cf {
    zoom:1
}
/* IE7 */

.div {
    height: 500px;
    width: 100%;
    display: block;
    position: relative;
}
#sectionA {
    background-color: #ABFF8F;
}
#sectionB {
    background-color: #FFDF80;
}
#sectionC {
    background-color: #A8E9FF;
    height: 100px !important;
    z-index: 1;
}
#footer {
    background-color: #666;
    color: #fff;
    font-weight: bold;
    font-size: 2em;
    z-index: 10;
    top:0;
}
.box {
    width:50px;
    margin: 0 20px 20px 0;
    height: 50px;
    display: block;
    background-color: #f2f2f2;
    float: left;
}

JavaScript

var $window = jQuery(window),
    $footer = jQuery("#footer"),
    $viewport = window.innerHeight,
    $startEffect = $footer.offset().top - $viewport;

function footerParallax() {
    var $scrollPos = $window.scrollTop() - $startEffect,
        $ratio = 0.6,
        $newTop = -($scrollPos * $ratio),
        $oldTop = parseInt($footer.css('top')),
        $nonRelTop = $footer.offset().top - $oldTop,
        $wanted = ($window.scrollTop()+$viewport-$footer.height());
    if ($nonRelTop + $newTop < $wanted) {
        $('#sectionC').css('display', 'none');
        $wanted = ($window.scrollTop()+$viewport-$footer.height());
        $nonRelTop = $footer.offset().top - $oldTop;
        $newTop = $wanted - $nonRelTop;
    } else {
        $('#sectionC').css('display', 'block');
    }    
    $footer.css('top', $newTop);
}

$window.scroll(footerParallax);