JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <em class="button" id="old">old button</em>
</div>

CSS

.button {
    display:inline-block;
    padding: 10px;
    cursor: pointer;
}
#old { background-color: yellow; }
#new { background-color: orange; }

JavaScript

var oldButton = '<em class="button" id="old">old button</em>'
var newButton = '<em class="button" id="new">new button</em>'
$('#old').click(function(){
    $('div').html(newButton);
});
$('#new').click(function(){
    $('div').html(oldButton);
});