JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>[content here]</li>
    <li>[content here]</li>
    <li>[content here]</li>
</ul>

JavaScript

$('li').slideUp({
    complete: function(){
        if($('li:last').is(this)){
            alert('done');
        }
    }
});