用JS制作一个点击向下滚动，点击返回顶部（用Tween函数）
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<script type="text/javascript" src="js/tween.js" ></script>
<style>
*{
margin: 0;padding: 0;
}
.test{
border: 1px red solid;
height: 98px;
line-height: 100px;
}
#down{
width: 100px;
line-height: 100px;
background: skyblue;
}
#top{
width: 100px;
line-height: 100px;
text-align: center;
background: skyblue;
position: fixed;
right: 10px;
bottom: 10px;
}
</style>
</head>
<body>
<input type="button" id="down" value='点击向下滚动'/>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<div class="test"></div>
<input type="button" id="top" value="点击返回顶部" />
<script type="text/javascript">
//获取当前TOP 还有down的ID
var oDown = document.getElementById('down');
var oTop = document.getElementById('top');
//兼容性写法
function setScrollerPos(aTop){
document.body.scrollTop = aTop;
document.documentElement.scrollTop = aTop;
}
function getScrollerPos(){
return document.body.scrollTop||document.documentElement.scrollTop;
}
//给按钮绑定一个事件，运动tween函数
oDown.onclick = function(){
//起始值
var start = 0;
//结束值
var end = 500;
//过程
var change = end - start;
//步数
var step = 0;
//最大走的步数
var stepMax = 30;
//设置一个计时器
var timer = setInterval(function(){
//步数增加
step++;
if(step>=stepMax){
//暂停计时器还有清空计时器
clearInterval(timer);timer=null;
}
//tween函数曲线
var t = Tween.Cubic.easeOut(step,start,change,stepMax);
//在可滚动条调用t
setScrollerPos(t);
}, 30);
}
//同上
oTop.onclick = function(){
var start = getScrollerPos();
//滚动条返回顶部就是滚动条位置等于0
var end = 0;
var change = end - start;
var step = 0;
var stepMax = 30;
var timer = setInterval(function(){
step++;
if(step>=stepMax){
clearInterval(timer);timer=null;
}
var t = Tween.Cubic.easeOut(step,start,change,stepMax);
setScrollerPos(t);
}, 30);
}
</script>
</body>
</html>
