parallax bg scroll

by Nikhil krishnan

HTML

<div class="wrapper">
    <span class="paralax-panel">dgzdf</span>
</div>

CSS

.wrapper{
    height:1500px;
    float:left;
    width:100%;
}
.paralax-panel{
    margin-top:200px;
    background-image:url(http://images.eurogamer.net/2014/usgamer/Banner-Saga-Screenshot-01.jpg); 
        display:block;  
    float:left;
    width:100%;
    height:200px;
}

JavaScript

//paralax
              ofSt = $('.paralax-panel').offset().top 
               $(window).scroll(function(){
                 var wSv = $(window).scrollTop();
                 nPs = wSv - ofSt

                 var bgpos = $('.paralax-panel').css('backgroundPosition').split(' ');

                 if( wSv > (ofSt - $(window).height()) ){
                 $('.paralax-panel')
                 .css('backgroundPosition', bgpos[0] + ' ' + nPs + 'px');
                 }
               });