JS实现短信验证码倒计时功能：按钮禁用与状态切换

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
*{margin: 0;padding: 0;}
.send{
width:250px;
margin:0 auto;
}
.send input{
display: block;
width:200px;
font:400 16px/30px "微软雅黑";
outline: none;
border: none;
}
.send button{
height:30px;
border: none;
outline: none;
font:400 16px/30px "微软雅黑";
text-align: center;
}
</style>
<script type="text/javascript">
window.onload=function(){
var button=document.getElementsByTagName("button")[0];
button.innerText="免费获取验证码";
var timer=null;
button.onclick=function(){
clearInterval(timer);//这句话至关重要
var time=6;
var that=this;//习惯
timer=setInterval(function(){
console.log(time);
if(time<=0){
that.innerText="";
that.innerText="点击重新发送";
that.disabled=false;
}else {
that.disabled=true;
that.innerText="";
that.innerText="剩余时间"+(time)+"秒";
time--;
}
},1000);
}
}
</script>
</head>
<body>
<div id="send">
<input type="text" name="in" id="in" value="" /><button></button>
</div>
</body>
</html>