0초 부터 초단위로 초올리기

js

startday = new Date(); 
clockStart = startday.getTime(); 

function initStopwatch() { 
  var myTime = new Date(); 
  return((myTime.getTime() - clockStart)/1000); 
} 

function getSecs() { 
  console.log('getSecs start');
  var tSecs = Math.round(initStopwatch()); 
  var iSecs = tSecs % 60; 
  var iMins = Math.round((tSecs-30)/60);   
  var sSecs ="" + ((iSecs > 9) ? iSecs : "0" + iSecs); 
  var sMins ="" + ((iMins > 9) ? iMins : "0" + iMins); 
  var timeRemain = sMins+":"+sSecs; 

 
  document.getElementById('clock').innerHTML = timeRemain;

  window.setTimeout('getSecs()',1000); 
} 


window.onload = window.setTimeout('getSecs()',1)

html

<span id="clock" class="txt_red"></span>

See the Pen 0초 부터 초단위로 초올리기 by younghyeong ryu (@wangta69) on CodePen.