JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<span id="sample-span">Sample Text</span>
<input type="button" value="click to run" onclick="runCode()" />

CSS

span {
    color: blue;
}
.colorized {
    color: red;
}

JavaScript

function runCode() {
  $("#sample-span").toggleClass("colorized");
  setTimeout(runTask,10)
}

function runTask(){
	for (var i = 0; i < 100000; i++) {
    console.log(new Date());
  }
  $("#sample-span").toggleClass("colorized");
}