JSFiddle - React, Tailwind, and code Playground

HTML

<button class="red btn" type="button" id="btn"  onclick="changeColor()">Click Me to toggle class</button>

CSS

.btn{
  padding:20px 10px;
  color:white;
  border:none;
}

.red{
  background-color:red;
}

.green{
   background-color:green;
}

JavaScript

function changeColor() {
    document.getElementById("btn").classList.toggle('red');
     document.getElementById("btn").classList.toggle('green');
}