JSFiddle - React, Tailwind, and code Playground

HTML

<div id="listsContainer">
    <ul>
        <li>lorem lipsum</li>
        <li>lorem lipsum</li>
    </ul>
    <ul>
        <li>lorem lipsum</li>
        <li>lorem lipsum</li>
        <li>lorem lipsum</li>
    </ul>
    <ul>
        <li>lorem lipsum</li>
        <li>lorem lipsum</li>
        <li>lorem lipsum</li>
        <li>lorem lipsum</li>
    </ul>
</div>

JavaScript

$("ul").each(function() {
    $( this ).find("li").addClass("total-elements"+ $(this).children().length );
    if($(this).children().length == 3) {
    	$(this).append( "<li></li>" );
    }
    if($(this).children().length == 2) {
    	$(this).append( "<li></li><li></li>" );
    }
});