1 setInterval("setDate(‘2018-12-24 12:20:45‘)",1000);
 2 
 3 function setDate(setTime){
 4 var date = new Date();//獲取系統當前時間
 5 var time = (date.getYear()+1900)+"-"+(date.getMonth()+1)+"-"+date.getDate() +" "+date.getHours()+":"+date.getMinutes()+":"+date.getSeconds();
 6 var setDate = new Date(setTime);
 
 7 var leftTime = setDate.getTime()- date.getTime();
 8 /*
 9  
10 var Day = parseInt(dg/86400000);
11 var hg = dg - Day*86400000;
12 var Hours = parseInt(hg/3600000);;
13 var mg = hg - Hours*3600000;
14 var Minutes = parseInt(mg/60000);
15 var sg = mg - Minutes*60000;
16 var s = parseInt(sg/1000);
17 var dTime = Day + " 天 "+Hours + " 時 "+Minutes + " 分 "+s + " 秒 ";
 
*/
18 
19 var d,h,m,s;
20 if (leftTime>=0) {
21 d = Math.floor(leftTime/1000/60/60/24);
22 h = Math.floor(leftTime/1000/60/60%24);
23 m = Math.floor(leftTime/1000/60%60);
24 s = Math.floor(leftTime/1000%60);
25 }
26 var dTime = d + " 天 "+h + " 時 "+m + " 分 "+s + " 秒 ";
27 
28  
29 //$("#time").html("倒計時:"+dTime);
30 }

Jquery之倒計時計算