a超链接之返回顶部的两种实现方法

1.通过css实现：

为页面顶部如body或者自己设置的盒子等加上唯一id属性

<body id="id">
....
<a href="#id">返回顶部</a>

2.js实现

通过设置标签滚动位置判断

document.body.scrollTop=0;
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .cs_top{
            position: fixed;
            right: 10px;
            bottom: 10px;
            height: 60px;
            width: 60px;
            background-color: darkgray;
            opacity: 0.5;
        }
        .js_top{
            position: fixed;
            right: 10px;
            bottom: 120px;
            height: 60px;
            width: 60px;
            background-color: rebeccapurple;
            opacity: 0.5;
        }
        .hide{
            display: none;
        }
        #content{
            height:960px;
            width: 100%;
        }
        #content:before{
            content: 'top';
            display: block;
        }
        body:after{
            content: 'end';
            display: block;
        }
    </style>
    <script>

    </script>
</head>
<body onscroll="Func();">
    <div id="content">
        <p>fdffa</p>
        <p>fdffa</p>
        <p>fdffa</p>
        <p>fdffa</p>
        <p>fdffa</p>
        <p>fdffa</p>
        <p>fdffa</p>
        <p>fdffa</p>
        <p>fdffa</p>
    </div>
    <div class="cs_top">
        <a href="#content">返回顶部</a>
    </div>
    <div class="js_top hide">
        <a href="javascript:void(0);" onclick="GoTop();">返回顶部</a>
    </div>
</body>
</html>
<script src="../02js拾遗/jquery.js"></script>
<script>
    function Func(){
        var scrollTop=document.body.scrollTop;
        var ele=document.getElementsByClassName('js_top')[0];
        if (scrollTop>50){
            ele.classList.remove('hide');
        }else{
            ele.classList.add('hide');
        }
    }

    function GoTop(){
        document.body.scrollTop=0;
    }

</script>
View Code

 

posted @ 2018-03-04 08:13  山上有风景  阅读(5498)  评论(0)  编辑  收藏  举报