本文实例讲述了JS实现的网页倒计时数字时钟效果，分享给大家供大家参考，具体实现方法如下：
效果图：
<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>javascript实现的倒计时时钟</title> <style> body,div{margin:0;padding:0;} body{color:#fff;font:16px/1.5 5fae8f6f96c59ed1;} #countdown{width:300px;text-align:center;background:#1a1a1a;margin:10px auto;padding:20px 0;} input{border:0;width:283px;height:50px;cursor:pointer;margin-top:20px;background:url(http://www.jb51.net/jscss/demoimg/201210/btn-1.png) no-repeat;} input.cancel{background-position:0 -50px;} span{color:#000;width:80px;line-height:2;background:#fbfbfb;border:2px solid #b4b4b4;margin:0 10px;padding:0 10px;} </style> <script> window.onload = function () { var oCountDown = document.getElementById("countdown"); var aInput = oCountDown.getElementsByTagName("input")[0]; var timer = null; aInput.onclick = function () { this.className == "" ? (timer = setInterval(updateTime, 1000), updateTime()) : (clearInterval(timer)); this.className = this.className == '' " : ''; }; function format(a) { return a.toString().replace(/^(d)$/,'0$1') } function updateTime () { var aSpan = oCountDown.getElementsByTagName("span"); var oRemain = aSpan[0].innerHTML.replace(/^0/,'') * 60 + parseInt(aSpan[1].innerHTML.replace(/^0/,'')); if(oRemain <= 0) { clearInterval(timer); return } oRemain--; aSpan[0].innerHTML = format(parseInt(oRemain / 60)); oRemain %= 60; aSpan[1].innerHTML = format(parseInt(oRemain)); } } </script> </head> <body> <div id="countdown"> <span>01</span>分钟<span>40</span>秒 <input type="button" value="" /> </div>代码特效 </body> </html>
如果觉得还不过瘾大家可以参考此专题进行深入学习：js倒计时汇总
希望本文所述对大家学习javascript程序设计有所帮助。