2种简单的js倒计时实现方法

//带天数的倒计时
function countDown(times){
  var timer=null;
  timer=setInterval(function(){
    var day=0,
      hour=0,
      minute=0,
      second=0;//时间默认值
    if(times > 0){
      day = Math.floor(times / (60 * 60 * 24));
      hour = Math.floor(times / (60 * 60)) - (day * 24);
      minute = Math.floor(times / 60) - (day * 24 * 60) - (hour * 60);
      second = Math.floor(times) - (day * 24 * 60 * 60) - (hour * 60 * 60) - (minute * 60);
    }
    if (day <= 9) day = &#39;0&#39; + day;
    if (hour <= 9) hour = &#39;0&#39; + hour;
    if (minute <= 9) minute = &#39;0&#39; + minute;
    if (second <= 9) second = &#39;0&#39; + second;
    //
    console.log(day+"天:"+hour+"小时："+minute+"分钟："+second+"秒");
    times--;
  },1000);
  if(times<=0){
    clearInterval(timer);
  }
}

//单纯分钟和秒倒计时
function resetTime(time){
  var timer=null;
  var t=time;
  var m=0;
  var s=0;
  m=Math.floor(t/60%60);
  m<10&&(m=&#39;0&#39;+m);
  s=Math.floor(t%60);
  function countDown(){
   s--;
   s<10&&(s=&#39;0&#39;+s);
   if(s.length>=3){
    s=59;
    m="0"+(Number(m)-1);
   }
   if(m.length>=3){
    m=&#39;00&#39;;
    s=&#39;00&#39;;
    clearInterval(timer);
   }
   console.log(m+"分钟"+s+"秒");
  }
  timer=setInterval(countDown,1000);
}