index.html

<!DOCTYPE html> <html lang='en'> 
<head> 
<meta charset='UTF-8' /> 
<title>timer</title> 
</head> 
<body> 
<span id= "days">00</span>:</span><span id= "hours">00</span>:<span id="minutes">00</span>:<span id="seconds">00</span>
<script> 
const minutes = document.querySelector("#minutes");
const seconds = document.querySelector("#seconds");
let count = 0; 
const renderTimer = () => { 
count += 1;
days.innerHTML = Math.floor(count / 86400).toString().padStart(2, "0");
let shours = Math.floor(count / 3600).toString().padStart(2, "0");
hours.innerHTML = (shours % 24).toString().padStart(2, "0");
let smin = Math.floor(count / 60).toString().padStart(2, "0");
minutes.innerHTML = (smin % 60).toString().padStart(2, "0");
seconds.innerHTML = (count % 60).toString().padStart(2, "0");
}
const timer = setInterval(renderTimer, 1000);
</script> 
</body> 
</html>