广告笔

*{
padding: 0;
    margin: 0;
}
.con{
    height: 3000px;
    position: relative;
}
.guanggao{
    position: absolute;
    right: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 100px;
    height: 300px;
    background: #0062CC;
}
.guanggao2{
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 100px;
    height: 300px;
    background: #0062CC;
}





var guanggao = $(.guanggao)[0]

$(window).scroll(function(){

    var top2 = innerHeight/2                            //父元素居中top:50%
    var top1= $(window).scrollTop()                     //父元素滚动偏移值
    console.log(top1)
    console.log(top2)
    $(.guanggao).animate({top:top1+top2},60)
})