JSFiddle - React, Tailwind, and code Playground

HTML

<div id="test" onclick="animate('test', 75);">0%</div>

CSS

#test {
  height: 25px;
  width: 25px;
  background: green;
  transition: width 3s ease;
  cursor: pointer;
}

JavaScript

function animate(elem, num) {
  var test = document.getElementById(elem);
  var width = test.offsetWidth;

  if(width == 25) {
    test.style.width = num + '%';
  } else {
    test.style.width = '25px';
  }
}