小数，分钟和秒的倒数计时器在达到0时发出警报

Question

当倒计时到达00:00:00

时，我需要提醒

<p>
<span id="hms">00:00:05</span>
</body>

<script>

    var startTime;
    function getCookie(name) {
      var value = "; " + document.cookie;
      var parts = value.split("; " + name + "=");
      if (parts.length == 2) return parts.pop().split(";").shift();
    } // credits kirlich @http://stackoverflow.com/questions/10730362/get-cookie-by-name

    function count() {
     if(typeof getCookie('remaining')!= 'undefined')
     {
       startTime = getCookie('remaining');
     }
     else if(document.getElementById('hms').innerHTML.trim()!='')
     {
       startTime = document.getElementById('hms').innerHTML;
     }
     else
     {
      var ddddd = new Date(); 
      var hhhhh=ddddd.getHours(); 
      var mmmmm=ddddd.getMinutes();
      var sssss=ddddd.getSeconds();
      startTime = hhhhh+':'+mmmmm+':'+sssss;
      //OR
      startTime  = ddddd.toTimeString().split(" ")[0]

     }

     var pieces = startTime.split(":");
     var time = new Date();
     time.setHours(pieces[0]);
     time.setMinutes(pieces[1]);
     time.setSeconds(pieces[2]);
     var timediff = new Date(time.valueOf()-1000)
     var newtime = timediff.toTimeString().split(" ")[0];
     document.getElementById('hms').innerHTML=newtime ;
     document.cookie = "remaining="+newtime;
     setTimeout(count,1000);

    }
    count();
</script>

</p