JSFiddle - React, Tailwind, and code Playground

HTML

<div id="time"></div>

JavaScript

var h = 17, m =25 ,s = 0;
var dateEnd = new Date();
dateEnd.setHours(h);
dateEnd.setMinutes(m);
dateEnd.setSeconds(s);
var elemOut = document.querySelector("#time");
(()=>{
var diff = dateEnd - new Date();
if(diff <= 0){
	elemOut.innerHTML = "Время закончилось!";
  return;
  }
  else{
  diff/=1000;
  var hour = Math.floor(diff/60/60).toString();
  hour = (hour.length< 2?"0":"")+hour;
  diff %= 60*60;
  var minutes = Math.floor(diff/60).toString();
  minutes = (minutes.length <2?"0":"")+minutes;
  diff %= 60;
  var seconds = diff.toString();
  seconds = seconds.length <2?"0":""+seconds;
  elemOut.innerHTML = hour+":"+minutes+":"+seconds;
  }
setTimeout(arguments.callee,1000);
})();