本文实例为大家分享了js周期性获取短信验证码的具体代码，供大家参考，具体内容如下
<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
</head>
<body>
<input type="text"/>
<input type="button" id="btn" value="点击发送验证码"/>
[removed]
var timerId = null;
var btn = document.getElementById("btn");
var num = 5;
btn.o
