话不多说，直接上代码
<html>
<head> <title>倒计时</title></head><body> <div id="time1"></div> <p>-----------------------</p> <div id="time2"></div></body><script src="https://code.jquery.com/jquery-3.4.0.min.js"></script><script type="text/javascript"> window.onload = function () { endTime(); } function endTime() { var myDate = new Date(); var timestamp = Date.parse(myDate) / 1000; var date = myDate.getDate(); var year = myDate.getFullYear(); var month = myDate.getMonth() + 1; var endtime1 = year + '-' + month + '-' + date + ' 12:00:00'; var endtime2 = year + '-' + month + '-' + date + ' 18:00:00'; var time1 = Date.parse(new Date(endtime1)) / 1000; var time2 = Date.parse(new Date(endtime2)) / 1000; if(time1 > timestamp) { $('#time1').text(time1 - timestamp +'S'); } if(time2 > timestamp) { $('#time2').text(time2 - timestamp +'S'); } setTimeout("endTime()", 1000); }</script></html>