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 diff = dateEnd - new Date();
if(diff <= 0){
	document.querySelector("#time").innerHTML = "Время закончилось!";
  return;
  }
  else{
  diff/=1000;
  document.querySelector("#time").innerHTML = (Math.floor(diff/60/60).toString().length< 2?"0":"")+ Math.floor(diff/60/60)+":";
  diff -= Math.floor(diff/60/60)*60*60;
  document.querySelector("#time").innerHTML += (Math.floor(diff/60).toString().length <2?"0":"")+Math.floor(diff/60)+":";
  diff -= Math.floor(diff/60)*60;
  document.querySelector("#time").innerHTML += (diff.toString().length <2?"0":"")+diff;
  }
setTimeout(arguments.callee,1000);
})();