版本：
文件：
- https://cdn.bootcdn.net/ajax/libs/easy-countdown/2.2.0/countdown.js
- https://cdn.bootcdn.net/ajax/libs/easy-countdown/2.2.0/countdown.min.js
- https://cdn.bootcdn.net/ajax/libs/easy-countdown/2.2.0/jquery.countdown.js
- https://cdn.bootcdn.net/ajax/libs/easy-countdown/2.2.0/jquery.countdown.min.js