JSFiddle - React, Tailwind, and code Playground

HTML

<div></div><div></div><div></div>

CSS

div {
  margin: .6em;
  width: 40px;
  height: 40px;
  outline: dashed 1px gray;
  float: left;
}
.hilight {
  background: orange;
}

JavaScript

Array.prototype.forEach.call(document.querySelectorAll('div'), e=>e.addEventListener('click', e=>e.target.classList.toggle('hilight')))