JSFiddle - React, Tailwind, and code Playground

HTML

<a id="trigger" href="#">Trigger</a>

<div id="test"></div>

CSS

#test {
  height: 300px;
  width: 300px;
  background-color: red;
  
  /* setup the css transitions */
  -webkit-transition: width 1s;
  -moz-transition: width 1s;
  transition: width 1s;
}

#test.small {
  width: 100px;
}

JavaScript

$("a#trigger").on('click', function(){
	$("div#test").toggleClass('small');
});