I'm Ashamed, Disqus

So if you’ve ever tried to leave a comment, on here or any other site that uses Disqus (“Discuss”) for commenting, you’ll notice that it has a little array of formatting buttons below the comment box that allow you to.. format your comment. Make things bold, underlined, or insert links. Cool, right? Yes, but if you look closely, you’ll notice that they’re inserting the appropriate HTML tag for whatever you just clicked. Which makes me wonder… how does Disqus deal with other HTML tags?