jquery网页倒计时效果，秒杀

function FreshTime(){
                  var endtime=new Date('2019-4-12 18:00:00');//结束时间
                  var nowtime = new Date();//当前时间
                  var lefttime=parseInt((endtime.getTime()-nowtime.getTime())/1000); 
                  d=parseInt(lefttime/3600/24);
                  h=parseInt((lefttime/3600)%24);
                  m=parseInt((lefttime/60)%60);
                  s=parseInt(lefttime%60);
               
                  document.getElementById("Time").innerHTML="还剩" + d+"天"+h+"小时"+m+"分"+s+"秒";
                  if(lefttime<=0){
                      document.getElementById("Time").innerHTML="秒杀已结束";
                      clearInterval(hh);
                      $(".operate_btn").show()
                      }
                  }
                  FreshTime();
                  var hh;
                  hh=setInterval(FreshTime,1000);

效果如下：