<!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>
.box{
width:100px;
height:100px;
background-color: green;
position:absolute;
left:0;
top:100px;
}
</style>
</head>
<body>
<div class="box " id="demo"></div>
<button id="btn">开始</button>
</body>
</html>
<script>
//点击开始按钮，盒子匀速向右边直线运动，到了距离左边500px 的时候自动停下来
var demo=document.getElementById("demo");
var btn=document.getElementById("btn");
var Timer=null;
var num=0;
btn.onclick=function()
{
Timer=setInterval(fn , 4);
function fn()
{
num++
if(num<=500)
{
demo.style.left=num+"px";
}
else{
clearInterval(Timer); //定时器清除就等于停止运动了。
}
}
}
</script>
