获取时间戳常用方法如下：

 

倒计时计算代码：

<script>         function countTime(time){             var nowTime=+new Date();             var futureTime=+new Date(time);             var times=(futureTime-nowTime)/1000;             var d=parseInt(times/60/60/24);             var h=parseInt(times/60/60%24);             var m=parseInt(times/60%60);             var s=parseInt(times%60);             return d+'天'+h+'小时'+m+'分'+s+'秒'         }         countTime('2018-9-10 18:00:00')         console.log( countTime('2021-4-23 21:00:00'));     </script>

 创建日期对象的两种方法