JSFiddle - React, Tailwind, and code Playground

by meo

HTML

<ul class="gallery"> 
    <li id="1"></li>
    <li id="2"></li>
    <li id="3"></li>
</ul>

JavaScript

var newList = [];

$(".gallery li").each(function(){
    newList.push("<li>Slide" + $(this)[0].id || "" + "</li>");
});

$("body").append( "<ul class='galleryNav'>" + newList.join("") + "</ul>" );