<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title></title>
<style>
*{margin:0;padding:0;text-decoration:none;}
body{padding:20px}
#container{width:600px;height:400px;border:3px solid #333;overflow:hidden;position:relative;margin:0 auto;}
#list{width:4200px;height:400px;position:absolute;z-index:1;}
#list img{float:left;}
#buttons{position:absolute;width:100px;height:10px;bottom:20px;left:250px;z-index:2;}
#buttons span{cursor:pointer;display:block;float:left;width:10px;height:10px;border:1px solid #FFF;border-radius:50%;background:#333;margin-right:5px;}
#buttons .on { background: orange;}
.arrow{position:absolute;display:none;width:40px;height:40px;line-height:40px;z-index:2;font-size:36px;text-align:center;font-weight:bold;top:180px;background-color:rgba(0,0,0,.3);color:#FFF;}
#prev{left:20px;}
#next{right:20px;}
#container:hover .arrow{display:block;}
.arrow:hover{background-color:rgba(0,0,0,.7);}
</style>
<script>
window.onload = function(){
var container = document.getElementById('container');
var list = document.getElementById('list');
var buttons = document.getElementById('buttons').getElementsByTagName('span');
var prev = document.getElementById('prev');
var next = document.getElementById('next');
var index=1;
function showButton(){
for (var i = 0; i < buttons.length ; i++) {
if( buttons[i].className == 'on'){
buttons[i].className = '';
break;
}
}
buttons[index - 1].className = 'on';
}
function animate(offset){
var newLeft=parseInt(list.style.left)+offset;
var time = 300;
var interval = 10;
var speed = offset/(time/interval);
function go(){
if((speed<0 && parseInt(list.style.left)>newLeft) || speed>0 &&parseInt(list.style.left)<newLeft){
list.style.left=parseInt(list.style.left)+speed+'px';
setInterval(go,interval);
}else{
list.style.left=newLeft+'px';
if(newLeft<-3000){
list.style.left = -600+'px';
}
if(newLeft>-600){
list.style.left = -3000+'px';
}
}
}
go();
}
next.onclick= function(){
if(index==5){
index=1;
}else{
index+=1;
}
showButton();
animate(-600);
}
prev.onclick=function(){
if(index==1){
index=5;
}else{
index-=1;
}
showButton();
animate(600);
}
for(var i=0;i<buttons.length;i++){
buttons[i].onclick=function(){
if(this.className=='on'){
return;
}
var myindex=parseInt(this.getAttribute('index'));
var om=-600*(myindex-index);
animate(om);
index=myindex;
showButton();
}
}
}
</script>
</head>
<body>
<div id="container">
<div id="list" style="left:-600px">
<img src="img/5.jpg" alt="" title="">
<img src="img/1.jpg" alt="" title="">
<img src="img/2.jpg" alt="" title="">
<img src="img/3.jpg" alt="" title="">
<img src="img/4.jpg" alt="" title="">
<img src="img/5.jpg" alt="" title="">
<img src="img/1.jpg" alt="" title="">
</div>
<div id="buttons">
<span index="1" class="on"></span>
<span index="2" class=""></span>
<span index="3" class=""></span>
<span index="4" class=""></span>
<span index="5" class=""></span>
</div>
<a href="#" id="prev" class="arrow"><</a>
<a href="#" id="next" class="arrow">></a>
</div>
</body>
</html>找到原因了，计时器用错了