JQuery实现倒计时效果

首先：引入jquery文件

<script type="text/javascript" src="http://www.cnblogs.com/Content/Phone/js/Answer.js?201402242021"></script>

然后写javascript代码

<script type="text/javascript">

    $(function () {
        timer;
    })
    var maxtime = 20 * 100;
    function CountDown() {
        if (maxtime >= 0) {
            seconds = Math.floor(maxtime / 100);
            milliseconds = Math.floor(maxtime % 100);
            seconds = seconds < 10 ? ("0" + seconds) : seconds;
            milliseconds = milliseconds < 10 ? ("0" + milliseconds) : milliseconds;
            $(".time").text(seconds + ":" + milliseconds);
            //if(maxtime == 5*60) alert('注意，还有5分钟!');
            if (maxtime == 270) {
                //$("#musicNear")[0].play();
            }
            maxtime -= 10;
        }
    }

    timer = window.setInterval(CountDown, 100);
</script>