倒计时不加锁老代码

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>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(img/btn-1.png) no-repeat;color:#fff;}
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 == '' ? "cancel" : '';    
    };
    
    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="start" />
</div>
</body>
</html>
倒计时 不加锁 老代码

倒计时不加锁老代码
