JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="container">
<li>1</li>
<li class="fixed">2</li>
<li>3</li>
<li class="fixed">4</li>
<li>5</li>
</ul>

<button id="addnew">add new</button>

JavaScript

$("#container").sortable();
$("#addnew").click(function() {
    $("#container").append("<li>new</li>");
});