javasctipt setInterval（）用法

<DIV id="CountMsg" class="HotDate">
<span id="t_d">00 天</span>
<span id="t_h">00 时</span>
<span id="t_m">00 分</span>
<span id="t_s">00 秒</span>

</DIV>

<script type="text/javascript">
function getRTime(){
var EndTime= new Date('2017/06/07 09:00:00'); //截止时间
var NowTime = new Date();
var t =EndTime.getTime() - NowTime.getTime();
var d=Math.floor(t/1000/60/60/24);
var h=Math.floor(t/1000/60/60%24);
var m=Math.floor(t/1000/60%60);
var s=Math.floor(t/1000%60);

document.getElementById("t_d").innerHTML = d + " 天";
document.getElementById("t_h").innerHTML = h + " 时";
document.getElementById("t_m").innerHTML = m + " 分";
document.getElementById("t_s").innerHTML = s + " 秒";
}
setInterval(getRTime,1000);

</script>