页面回到顶部

1.html页面<div style="display: none;" id="rocket-to-top">
<div style="opacity:0;display: block;" class="level-2"></div>
<div class="level-3"></div>
</div>2.样式设置
*{list-style:none;border:0;}
#rocket-to-top div {
left: 0;
margin: 0;
overflow: hidden;
padding: 0;
position: absolute;
top: 0;
width: 149px;
}
#rocket-to-top .level-2 {
background: url("../images/rocket_button_up.png") no-repeat scroll -149px 0 transparent;
display: none;
height: 250px;
opacity: 0;
z-index: 1;
}
#rocket-to-top .level-3 {
background: none repeat scroll 0 0 transparent;
cursor: pointer;
display: block;
height: 150px;
z-index: 2;
}
#rocket-to-top {
background: url("../images/rocket_button_up.png") no-repeat scroll 0 0 transparent;
cursor: default;
display: block;
height: 250px;
margin: -125px 0 0;
overflow: hidden;
padding: 0;
position: fixed;
right: 0;
top: 80%;
width: 149px;
z-index: 11;
}
3.js设置
$(function() {
var e = $(".topExper"),
t = $(document).scrollTop(),
n,
r,
i = !0;
$(window).scroll(function() {
var t = $(document).scrollTop();
if(t==0){
$("#yuyue").hide();
$("#top").hide();
$("#yuyue1").show();
}else{
$("#yuyue").show();
$("#top").show();
$("#yuyue1").hide();
}
}),
$("#top").click(function() {
function t() {
var t = e.css("background-position");
if (e.css("display") == "none" || i == 0) {
clearInterval(n);
$("#yuyue").hide();
$("#top").hide();
$("#yuyue1").show();
return
}
switch (t){
case "0px 0px":
e.css("background-position", "-298px 0px");
break;
case "-298px 0px":
e.css("background-position", "-447px 0px");
break;
case "-447px 0px":
e.css("background-position", "-596px 0px");
break;
case "-596px 0px":
e.css("background-position", "-745px 0px");
break;
case "-745px 0px":
e.css("background-position", "-298px 0px");
}
}
if (!i) return;
n = setInterval(t, 50),
$("html,body").animate({scrollTop: 0},"slow");
});
});