JSFiddle - React, Tailwind, and code Playground

HTML

<h1 class='myElement'>
  <div id='yourElement'>
     WATCH ME CHANGE COLORS, BRO
  </div>
</h1>

CSS

.myElement {
  color: red;
}
.changeColor {
  color: blue;
}

JavaScript

var function1 = function() {
	alert('Observe that I, function1, execute before the lowly function2');
}

var function2 = function() {
	document.getElementById("yourElement").className = "changeColor";
}

function1();
function2();