JSFiddle - React, Tailwind, and code Playground

HTML

<span id="btn">add div</span>
<span id="btnspn">add class</span>

CSS

#btn{
    cursor:pointer;
    background:yellow;
    padding:5px;
}
.blue{
    background:blue;
}

JavaScript

$(function() {
    $('#btn').click(function(){
        $('body').append('<div id="dydiv" style="width:30px;height:30px;border:1px solid black"></div>');
    }); 
});

$(document).on("click","#btnspn",function(){
$("#dydiv").addClass("blue");
});