javascript 体验倒计时：距离国庆还有多长时间

 <!DOCTYPE html>

 <html lang="en">

 <head>

     <meta charset="UTF-8">

     <title>Document</title>

     <style>

         div {

             width: 1210px;

             margin: 200px auto;

             color: orange;

             text-align: center;

             font: 600 30px/30px "simSun";

         }

     </style>

 </head>

 <body>

     <div></div>

     <script>

         var div = document.getElementsByTagName("div")[0];

         var timer = setInterval(fn,500);

         function fn(){

             var nowtime = new Date();

             var future = new Date("2018/10/01 10:10:10");

             var timeSum = future.getTime() - nowtime.getTime();

             var day = parseInt(timeSum/1000/60/60/24);

             var hour = parseInt(timeSum/1000/60/60%24);

             var minu = parseInt(timeSum/1000/60%60);

             var sec = parseInt(timeSum/1000%60);

             // var millsec = parseInt(timeSum%1000);

             day = day < 10? "0"+day:day;

             hour = hour < 10? "0"+hour:hour;

             minu = minu < 10? "0"+minu:minu;

             sec = sec < 10? "0"+sec:sec;

             // if (millsec < 10) {

             //     millsec = "00"+millsec;

             // }else if (millsec < 100) {

             //     millsec = "0"+millsec;

             // }

             if (timeSum < 0) {

                 div.innerHTML = "距离国庆节还有00天00小时00分00秒";

                 clearInterval(timer);

                 return;

             }

             div.innerHTML = "距离国庆节还有"+day+"天"+hour+"小时"+minu+"分"+sec+"秒";

         }

     </script>

 </body>

 </html>