JSFiddle - React, Tailwind, and code Playground

HTML

<div id="showValue" class="button">(Click) Show data-demo attribute</div>

<div class="update button">(Click) Update text and data-demo attribute</div>
<br>
<div class="value" data-demo="not updated">Not updated</div>

CSS

.button{
    display:block;
    padding:5px;
    margin:5px;
    background:#ccc;
    color:#fff;
    cursor:pointer;
}

JavaScript

$('#showValue').click(function(){
    alert($('.value').data('demo'));
});

$('.update').click(function(){
   $('.value').text('updated').attr('data-demo', 'updated');
});