<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>Document</title>
<style>
#demo{
100px;
height:100px;
background-color: pink;
position:absolute;
top:30px;
left:0;
}
#demo2{
200px;
height:200px;
background-color: green;
position: absolute;
left:0;
top:200px;
}
</style>
</head>
<body>
<button id="btn300">300</button>
<button id="btn600">600</button>
<div id="demo"></div>
<div id="demo2"></div>
</body>
</html>
<script>
function $id(id){return document.getElementById(id);}
var timer=null;
$id("btn300").onclick=function (){
run($id("demo"),300);
run($id("demo2"),600);
}
$id("btn600").onclick=function () {
run($id("demo"),600);
run($id("demo2"),300);
}
function run(obj,target)
{
var speed=(target-obj.offsetLeft)>0 ? 10 : -10; //用来判断应该往前走还是后退
clearInterval(obj.timer);
obj.timer=setInterval(function(){
var result=target-obj.offsetLeft; //盒子距离目标位置的距离
if(Math.abs(result)<=10) //盒子距离目标位置的距离在步长10以内时，说明到位置了，因为不会在10以内
{
obj.style.left=target+"px";
clearInterval(obj.timer);
}
else{
obj.style.left=obj.offsetLeft+speed+"px";
}
},10)
}
</script>