JS实现获取时间和设置倒计时代码分享

<script type="text/javascript">
    var timeBox = document.querySelector("#time");    function countdown(){
      var nowTime = new Date();      var targetTime = new Date("2018/2/27 15:44:15");      var spanTime = targetTime-nowTime;      if(spanTime <=0){
        timeBox.innerHTML="立即抢购";
        clearInterval(countdown);
      }else{        var hours = Math.floor(spanTime/(1000*60*60));
      spanTime-=hours*60*60*1000;      var minute = Math.floor(spanTime/(1000*60));
      spanTime-=minute*60*1000;      var second = Math.floor(spanTime/1000);
      hours<10 ? hours='0'+hours : hours;
      minute<10 ? minute='0'+minute : minute;
      second<10 ? second='0'+second : second;
      timeBox.innerHTML=hours+':'+minute+':'+second;
      }

    }    var timer = window.setInterval(countdown,1000);  </script>

<script type="text/javascript">
    var timeBox = document.querySelector("#time");    function countdown(){
      var date = new Date();      var hours = date.getHours();      var minute = date.getMinutes();      var second = date.getSeconds();
      hours =checkTime(hours);
      minute =checkTime(minute);
      second =checkTime(second);
      timeBox.innerHTML = hours+':'+minute+':'+second;
    }    // 检测时间数字是否小于10，在小于10的数字前加一个‘0’
    function checkTime(i){
      i<10 ? i="0"+i :i;      return i;
    }    var timer = window.setInterval(countdown,1000);  </script>