<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>setInterval方法的使用</title>
<style>
div{
width: 200px;
height: 200px;
background-color: red;
position: absolute;
top:50px;
}
</style>
</head>
<body>
<button>点我</button>
<div></div>
<script>
function $(selector){
return document.querySelector(selector);
}
var num = 0;
$('button').onclick = function(){
//开启定时器，占内存
var Timer = setInterval(function(){
if (num > 600){
//停止定时器
clearInterval(Timer)
}
num += 20;
$('div').style.left = num + 'px';
},100);
};
</script>
</body>
</html>