JSFiddle - React, Tailwind, and code Playground

HTML

<div id='message'>Default message</div>
<input type='button' onclick='Run();' value='start'>

JavaScript

function Run() {
	var delay = 3000;	//-- 3 seconds
	$( '#message' ).text('Please wait ' + delay + ' seconds...');
	var start = new Date().getTime();
	while (true) {
		current = new Date().getTime();
		if ( (start + delay) < current) {
			break;
		}
	}
	$( '#message' ).text('Done');
}