JSFiddle - React, Tailwind, and code Playground

HTML

<div id="target" style="display:none">
</div>

JavaScript

var target,
    allotedTimeForWork=10000   /*you can change this*/
    ;
var handler = setTimeout(function(){
      if(!target)
      {
          target=document.getElementById('target');
      }
    target.style.display="block";
    startTicker();
}, allotedTimeForWork);

function startTicker()
{
    var counter=10;
    var tickerHandler= window.setInterval(function(){
          if(counter>0)
          {
              target.innerHTML="you have "+counter +" seconds left";
              counter--;
          }
        else
        {
            target.innerHTML="time over";
            clearInterval(tickerHandler);
        }
    },1000);          
}