1 <!DOCTYPE html> 2 <html> 3 <head lang="en"> 4 <meta charset="UTF-8"> 5 <title>倒计时</title> 6 </head> 7 <body> 8 9 </body> 10 <script type="text/javascript"> 11 function timer(targetTime){ 12 var date = new Date(); 13 var dateTarget = new Date(targetTime); 14 var timeTarget = dateTarget.getTime(); 15 var time = date.getTime(); 16 if(timeTarget<time){ 17 return "目标时间不能小于当前时间"; 18 } 19 var time_difference = timeTarget-time; 20 var hour_point = time_difference/(1000*60*60); 21 var hour = Math.floor(hour_point); 22 var hour_difference = hour_point-hour; 23 var minute_point = hour_difference*60; 24 var minute = Math.floor(minute_point); 25 var minute_difference = minute_point - minute; 26 var second = Math.floor(minute_difference*60); 27 if(Number(hour)==0 && Number(minute)==0 && Number(second)==0){ 28 return "时间到"; 29 } 30 var timeStr = "还有 "+addZero(hour)+"小时 "+addZero(minute)+"分钟 "+addZero(second)+"秒 到时"; 31 return timeStr; 32 }; 33 34 var timeFun = setInterval(function(){ 35 var time_ = timer("2017/3/31 22:25:00"); 36 37 document.body.innerHTML = time_; 38 39 if(time_ == "时间到" || time_=="目标时间不能小于当前时间"){ 40 clearInterval(timeFun); 41 } 42 43 },1000); 44 45 function addZero(time){ 46 return time<0?"0"+time:time; 47 } 48 49 </script> 50 </html>
原文：http://www.cnblogs.com/woaiqiaodaima/p/6660124.html