JSFiddle - React, Tailwind, and code Playground

HTML

<div id="txt" onload="startTime()"></div>

JavaScript

function startTime()
{
var today=new Date();
var h=today.getHours();
var m=today.getMinutes();
var s=today.getSeconds();
// add a zero in front of numbers<10
m=checkTime(m);
s=checkTime(s);
document.getElementById('txt').innerHTML=h+":"+m+":"+s;
t=setTimeout('startTime()',500);
}

function checkTime(i)
{
if (i<10)
{
i="0" + i;
}
return i;
}