JSFiddle - React, Tailwind, and code Playground

HTML

<button>Button</button>

CSS

.bye-bye {
    background-color: #333;
}
button {
    color: #fff;
    transition: all 1s ease;
}

JavaScript

var button = document.querySelector('button');

button.addEventListener('mouseover', function() {
   button.classList.add('bye-bye'); 
});

button.addEventListener('transitionend', function(e) {
    console.log(e);
    button.parentNode.removeChild(button);
});