JSFiddle - React, Tailwind, and code Playground

HTML

<body onload='timer=setInterval("countUP()", 1000 );'>
<div id="timer_container">0</div>
</body>

CSS

#digital {
    font-size: 40px;
    text-align: center;
    top: -200px;
  }

JavaScript

var counter = 0
var timer;
function countUP () {
 counter = counter + 1;//increment the counter by 1
 //display the new value in the div
 document.getElementById("timer_container").innerHTML = counter;
 }