jQuery滚动到特定位置时出现 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <meta name="viewport" content="width=device-width,initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no" />
    <style type="text/css">
        *{margin:0; padding:0;}
        body{ max-width: 640px; margin:0 auto; }
        .box{ display: block;  height: 50px; line-height: 50px;text-align: center; border:1px solid #ccc; border-radius: 20px; background-color: #ddd; margin-top: 30px; position: fixed; bottom: 0; left: 0; width: 100%; z-index: 9 }

    </style>
</head>
<body>
    <div style="height:300px;background-color: #B15F5F"></div>
    <div style="height:100px;background-color: #619A51" id="demo">当滚到到这个div，隐藏下面的按钮</div>
    <div style="height:300px;background-color: #645FB1" ></div>
    <div style="height:200px;background-color: #F18733"></div>
    <a href="javascript:;" class="box" id="btn">按钮</a>
    <script src="http://apps.bdimg.com/libs/jquery/1.9.1/jquery.min.js" type="text/javascript"></script>
    <script type="text/javascript">
        $(function(){
        var demoHeight = $("#demo").offset().top;
        window.onscroll=function(){
            var this_scrollTop = $(this).scrollTop();
            if(this_scrollTop>demoHeight ){
                $("#btn").hide();
            }else{
                $("#btn").show();
            }
        };
    });
    </script>
    
</body>
</html>

效果图：

 

posted @ 2018-04-02 17:12  前端HL  阅读(508)  评论(0)  编辑  收藏  举报