JSFiddle - React, Tailwind, and code Playground
HTML
<p>p</p>
<p id="foo">
bar
<span>foo</span>
<span>descendants</span>
</p>
<p>p</p>
JavaScript
var foo = document.getElementById('foo');
while(foo.childNodes.length)
foo.parentNode.insertBefore(foo.childNodes[0], foo);
foo.parentNode.removeChild(foo);