<SCRIPT>
  window.onload = () => {
    startTime();
  }

  function startTime(){
    var time= new Date();
    hours= time.getHours();
    mins= time.getMinutes();
    secs= time.getSeconds();
    startTime= hours*3600+mins*60+secs;  //시간(hours*3600),분(mins*60),초 를 초로 환산하는 수식
    closeTime = startTime + 5; //startTime + 5 = 종료시간
    document.querySelector(".closetime").innerText = "Start Time : "+hours+" : "+mins+" : "+secs+" : ( closeTime : "+closeTime+")";
    Timer();
  }

  function Timer(){
    var time= new Date();
    hours= time.getHours();
    mins= time.getMinutes();
    secs= time.getSeconds();
    curTime=hours*3600+mins*60+secs
    if (curTime>=closeTime){
      console.log("function_start!!");  //함수 실행
    }else{
      window.setTimeout("Timer()",1000);
      document.querySelector(".timer").innerText = "Timer : "+hours+" : "+mins+" : "+secs+" : ("+curTime+")";
    }
  }
</SCRIPT>