JSFiddle - React, Tailwind, and code Playground

HTML

<a id="mybutton">Button</a>

CSS

#mybutton { display: block; background: red; color: #fff; height: 20px; width: 1000px; }
#mybutton.done { background: green; }

JavaScript

$("#mybutton").click(function () {
    var $this = $(this);
	$.ajax({
  		url: "http://fiddle.jshell.net/favicon.png",
  		beforeSend: function ( xhr ) {
    		xhr.overrideMimeType("text/plain; charset=x-user-defined");
  		}
	}).done(function ( data ) {
  		$this.addClass("done");
	});
});