模仿手机qq空间头部向上滚动颜色加深 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="jquery.js"></script>
<style>
    .banner{
        position:fixed;
        top:0;left:0;
        width:100%;
        height:100px;
        background:blue;

    }
</style>
</head>
<body>
<div class="banner"></div>
<div style="height:5000px;background:green;"></div>
<script>
    $(".banner").css("opacity",'0')
    $(window).scroll(function(){
        var scrollTop=$(window).scrollTop();
        var screenHeight=$(window).height();
        $(".banner").css("opacity",scrollTop/screenHeight);
    })
</script>
</body>
</html>

　　

posted @ 2017-02-14 09:26  刘浩2561179983  阅读(274)  评论(0)    收藏  举报