JSFiddle - React, Tailwind, and code Playground

HTML

<div id="editor" >
    <pre contentEditable="true">1</pre>
    <pre contentEditable="true">2</pre>
    <pre contentEditable="true">3</pre>
</div>

JavaScript

var container = document.getElementById('editor'),
    firstChild = container.childNodes[1];
if (container && firstChild) {
    var newPre = document.createElement('pre');
    newPre.setAttribute("contentEditable", "true");
    newPre.innerHTML = "boom";  
    firstChild.parentNode.insertBefore(newPre, firstChild.nextSibling);    
}