JS点击按钮自动倒计时代码，示例一：要求用户阅读完条款内容才能激活按钮；示例二：要求用户激活短信通道向用户手机发送验证码。-JS, click on the button automatic countdown code example 1: requires the user to read clause content can activate button　Example 2: ask users to activate SMS channel to users send verification code.