效果：
javascript：
<script type="text/javascript"> function counttime() { //获取当前时间 var date = new date(); var now = date.gettime(); //设置截止时间 var enddate = new date("2018-10-25 00:00:00"); var end = enddate.gettime(); //时间差 var differtime = end - now; //定义变量,h,m,s保存倒计时的时间 var h, m, s; if (differtime >= 0) { h = math.floor(differtime / 1000 / 60 / 60); m = math.floor(differtime / 1000 / 60 % 60); s = math.floor(differtime / 1000 % 60); h = h < 10 ? ("0" + h) : h; m = m < 10 ? ("0" + m) : m; s = s < 10 ? ("0" + s) : s; document.getelementbyid("_h").innerhtml = h + "时"; document.getelementbyid("_m").innerhtml = m + "分"; document.getelementbyid("_s").innerhtml = s + "秒"; settimeout(counttime, 1000); } else { document.getelementbyid("_h").innerhtml = "00时"; document.getelementbyid("_m").innerhtml = "00分"; document.getelementbyid("_s").innerhtml = "00秒"; } } </script>
html:
<body onload="counttime()"> <p class="timer"> <span id="_h"></span> <span id="_m"></span> <span id="_s"></span> </p></body>
以上就是js如何实现简单的时分秒倒计时效果（代码示例）的详细内容。