JSFiddle - React, Tailwind, and code Playground

HTML

<!-- clock.html -->
<!DOCTYPE HTML>
<html>
 <head>
  <title>Clock</title>
  <script src="clock.js"></script>
  <link rel="stylesheet" href="clock.css">
 </head>
 <body>
  <p>The time is: <output id="clock"></output></p>
 </body>
</html>

CSS

output { font: 2em sans-serif; }

JavaScript

setTimeout(function () {
    document.getElementById('clock').innerHTML = new Date();
}, 10);