JSFiddle - React, Tailwind, and code Playground

HTML

<ol class="btns" id="1">
  <li>First item</li>
  <li>Second item</li>
  <!--Third one goes here-->
  <li>Four item</li>
</ol>

JavaScript

var paragraph = document.createElement("li");
var textNode = document.createTextNode("Third item");
paragraph.appendChild(textNode);
var list=document.getElementById("1");
list.insertBefore(paragraph,list.childNodes[4]);