JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://raw.github.com/gist/1044128/0733e673144f3437114df0f144f4993af8b09e8e/outerHTML.js"></script>
<span>foo</span>

JavaScript

window.onload = function() {
    document.getElementsByTagName('span')[0].outerHTML = '<span>bar</span>';
};