倒计时

<p id="timeTxt"></p>

<script type="text/javascript">

function add(m){
　　return m<10 ? "0"+m : m;
}
var time2 = new Date().getTime();
function getTime(time){
　　var nowTime = new Date("2018-12-15 12:30:00").getTime();
　　var TimeCon = (nowTime - time)/1000;
　　TimeCon = parseInt(TimeCon);
　　var d = parseInt(TimeCon/(60*60*24));
　　var h = parseInt(TimeCon/(60*60)%24);
　　var m = parseInt(TimeCon/60%60);
　　var s = parseInt(TimeCon%60);
　　return d+"天"+add(h)+"小时"+add(m)+"分钟"+add(s)+"秒";
}

setInterval(function(){
　　var that = this;
　　time2 +=1000;
　　console.log(time2);
　　document.getElementById("timeTxt").innerHTML = that.getTime(time2);
　　console.log(that.getTime(time2));
},1000);

</script>