JSFiddle - React, Tailwind, and code Playground

HTML

<html>
    <head>
   
        <head>
   <body>
       <div>This is a div with no Class</div>
            </body>       
    
    <html>

CSS

div{background-color:blue;color:white;}

.red{background-color:red;}

JavaScript

$(document).ready(function(){

    $('div').click(function(){
    $(this).addClass('red');
        
    });

});