JSFiddle - React, Tailwind, and code Playground

HTML

<div id="mydiv">
    This is test of css change event
</div>
<button>Change Class</button>

CSS

.Divcss{
     color: green;
    font-size: 30px;
    padding: 0 7px 0 10px;
    width: 200px;
}

JavaScript

$("button").click(function(){
    $("#mydiv").addClass("Divcss").trigger('cssChange')
});
     
$("#mydiv").bind('cssChange', function(){ alert('test'); });