JSFiddle - React, Tailwind, and code Playground

HTML

<div class="timer" onload="starttimer()">
  <div>Section</div>
  <div class="time">
    <strong>Time left: <span id="time">00:00</span></strong>
  </div>
</div>

JavaScript

function timer(duration) {
	alert(duration);
}
function starttimer() {
	alert();
	timer(30*60);
}