js 倒计时

<script LANGUAGE="javascript">
//获取服务器时间当前剩余秒数
var seconds;
$.ajax({
type: "GET",
url: "time.php",
data:   "",
success: function(msg){
seconds = msg;
showtime( seconds );
window.setInterval(timedown,1000);
}
});

//自减秒数
function timedown(){
seconds--;
showtime(seconds);
}

//倒计时
function showtime( leftSecond ) {
leftSecond = parseInt(leftSecond);

if(leftSecond > 0){
var day = Math.floor(leftSecond/(24*3600));
leftSecond = parseInt((leftSecond%(24*3600)));
var hour = Math.floor(leftSecond/3600);
leftSecond = parseInt(leftSecond%3600);
var minute = Math.floor(leftSecond/60);
var second = leftSecond%60;
var countdown = '秒杀 '+day+'天 '+hour+'小时 '+minute+'分钟 '+second+'秒';

$('.miao p').eq(0).html(countdown);
}else if(leftSecond <= 0){
$('.miao p').eq(0).html('进行中...');
}

}
</script>