用JS写一个倒计时，从页面获取的数据。见详情

Question

<div id="exam-time"class="ub ub-ac ufr">                <span id="exam-countdown" >                     结束倒计时：10:00:00                </span>                                  秒从59到0                 分钟-1，                 分钟-60小时-1，                                  小菜鸟谢谢大家了！

Answer 1

demo