It's been mostly tested and seems to work fine, so I'm opening it for review.

Okay, after fixing the most stupid mistake ever (return failure if validate is true), I have actually gotten all of my test posts rendering correctly.

@Taeir

I'm a bit curious though why the "sticky" flag (/y) is set on the regexes and what the effect of that is on your regex. Does that ensure it doesn't match inside of another match?

The y flag indicates that the regex attempts to match the target string only from the index indicated by the lastIndex property (and unlike a global regex, does not attempt to match from any later indexes).

(MDN)