关于返回顶部这个功能，绝大部分网站都有用到，算是一个细节方面的小东西，个人觉得天猫的返回顶部这个小东西做的挺好，下面便是我模仿它的代码：
HTML：
</!DOCTYPE html>
<html>
<head>
<title>返回顶部,模仿某猫</title>
<link rel="stylesheet" type="text/css" href="css.css">
</head>
<body id="page">
<h1>返回顶部</h1>
<h2>返回顶部</h2>
<h3>返回顶部</h3>
<h4>返回顶部</h4>
<h5>返回顶部</h5>
<h1>返回顶部</h1>
<h2>返回顶部</h2>
<h3>返回顶部</h3>
<h4>返回顶部</h4>
<h5>返回顶部</h5>
<h1>返回顶部</h1>
<h2>返回顶部</h2>
<h3>返回顶部</h3>
<h4>返回顶部</h4>
<h5>返回顶部</h5>
<h1>返回顶部</h1>
<h2>返回顶部</h2>
<h3>返回顶部</h3>
<h4>返回顶部</h4>
<h5>返回顶部</h5>
<h1>返回顶部</h1>
<h2>返回顶部</h2>
<h3>返回顶部</h3>
<h4>返回顶部</h4>
<h5>返回顶部</h5>
<script type="text/javascript" src="jquery.min.js"></script>
<script type="text/javascript" src="script.js"></script>
</body>
</html>
CSS：
#gotoTop {
box-sizing: border-box;
display: none;
position: fixed;
bottom: 10%;
right: 20px;
cursor: pointer;
padding: 9px 2px;
width: 40px;
height: 40px; text-align : center;
border: 1px solid #e0e0e0;
z-index: 99;
background: #000
url("data:image/png;base64,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");
background-size: 100% auto;
text-align: center;
}
#gotoTop {
_position: absolute;
_top: expression(documentElement.scrollTop + documentElement.clientHeight * 3/
4 + "px")
}
#gotoTop.hover {
background: #165ec5
url("data:image/png;base64,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");
text-decoration: none;
background-size: 100% auto;
}
.fay-tip:hover p{
display:block;
transform-origin: 100% 0%;
-webkit-animation: topFadeIn 0.4s ease-in-out;
animation: topFadeIn 0.4s ease-in-out;
}
.fay-tip p{
display:none;
background-color: #494949;
padding: 10px;
width: 80px;
position: absolute;
box-shadow: 1px 1px 1px rgba(0, 0, 0, 0.2);
right: 38px;
color: #FFF;
font-size: 13px;
line-height: 1.4;
top:0;
margin: 0 0 10px;
}
.fay-tip p:before{
position: absolute;
content: '';
width:0;
height: 0;
border:6px solid transparent;
border-bottom-color:#494949;
right:-12px;
top:10px;
border-color: transparent transparent transparent #494949;
}
.fay-tip p:after{
width:100%;
height:40px;
content:'';
position: absolute;
top:0;
left:80px;
}
@-webkit-keyframes topFadeIn {
0% {
right:80px;
opacity:0;
transform: scale(0.6);
}
100% {
right:38px;
opacity:100%;
transform: scale(1);
}
}
@keyframes topFadeIn {
0% {
right:80px;
opacity:0;
}
100% {
right:38px;
opacity:100%;
}
}
JS：
gotoTop();
function gotoTop(min_height) {
// 预定义返回顶部的html代码，它的css样式默认为不显示
var gotoTop_html = '<div id="gotoTop" class="fay-tip"><p>返回顶部</p></div>';
// 将返回顶部的html代码插入页面上id为page的元素的末尾
$("#page").append(gotoTop_html);
$("#gotoTop").click(// 定义返回顶部点击向上滚动的动画
function() {
$('html,body').animate({
scrollTop : 0
}, 700);
}).hover(// 为返回顶部增加鼠标进入的反馈效果，用添加删除css类实现
function() {
$(this).addClass("hover");
}, function() {
$(this).removeClass("hover");
});
// 获取页面的最小高度，无传入值则默认为600像素
min_height ? min_height = min_height : min_height = 0;
// 为窗口的scroll事件绑定处理函数
$(window).scroll(function() {
// 获取窗口的滚动条的垂直位置
var s = $(window).scrollTop();
// 当窗口的滚动条的垂直位置大于页面的最小高度时，让返回顶部元素渐现，否则渐隐
if (s > min_height) {
$("#gotoTop").fadeIn(100);
} else {
$("#gotoTop").fadeOut(200);
}
});
}
至于jQuery就不用介绍了，基本上大家都了解，希望帮助那些纠结于实现返回顶部的朋友们。