I was directed to the Linkify project on GitHub (https://github.com/cowboy/javascript-linkify) for finding and \"linkifying\" URLs and domains just floating in text.
You'll need to replace the textNode with an HTML element, like a span, and then set your linkified-text as that element's innerHTML.
var replacementNode = document.createElement('span');
replacementNode.innerHTML = linkify(n.textContent);
n.parentNode.insertBefore(replacementNode, n);
n.parentNode.removeChild(n);