JSFiddle - React, Tailwind, and code Playground

HTML

<button id='fa-wave-square' style="color: crimson">
 Test
</button>

<button onClick="changeColor()">
  Click Me
</button>

JavaScript

function changeColor(){
 	el = document.getElementById("fa-wave-square");
  if(el.style.color === 'crimson'){
  	el.style.color = 'white';
  } else {
  	el.style.color = 'crimson';
  }
 }