That's John Gruber’s regex pattern for matching URL's (⌐■_■).

This is an example of the old adage that “When you use a regex to solve a problem, you end up with two problems.”

Looks like an URL matcher of some sorts, not limited to HTTP. Kudos for handling parentheses as valid URL characters.

The regex fucks with the markdown, so I had to put them in code tags:

[1] https://regex-vis.com/?r=%5Cb%28%28%3F%3A%28%3F%3A%5Ba-z%5D%5B%5Cw-%5D%2B%3A%29%3F%28%3F%3A%2F%7B1%2C3%7D%7C%5Ba-z0-9%25%5D%29%7Cwww%5Cd%7B0%2C3%7D%5B.%5D%7C%5Ba-z0-9.%5C-%5D%2B%5B.%5D%5Ba-z%5D%7B2%2C4%7D%2F%29%28%3F%3A%5B%5E%5Cs%28%29%3C%3E%5D%2B%7C%5C%28%28%5B%5E%5Cs%28%29%3C%3E%5D%2B%7C%28%5C%28%5B%5E%5Cs%28%29%3C%3E%5D%2B%5C%29%29%29*%5C%29%29%2B%28%3F%3A%5C%28%28%5B%5E%5Cs%28%29%3C%3E%5D%2B%7C%28%5C%28%5B%5E%5Cs%28%29%3C%3E%5D%2B%5C%29%29%29*%5C%29%7C%5B%5E%5Cs%60%21%28%29%5C%5B%5C%5D%7B%7D%3B%3A%27%22.%2C%3C%3E%3F%C2%AB%C2%BB%E2%80%9C%E2%80%9D%E2%80%98%E2%80%99%5D%29%29

[2] https://regexper.com/#\b((?:(?:[a-z][\w-]%20:)?(?:\/{1,3}|[a-z0-9%])|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}\/)(?:[^\s()%3C%3E]+|\(([^\s()%3C%3E]+|(\([^\s()%3C%3E]+\)))*\))+(?:\(([^\s()%3C%3E]+|(\([^\s()%3C%3E]+\)))*\)|[^\s%60!()\[\]{};:'%22.,%3C%3E?%C2%AB%C2%BB%E2%80%9C%E2%80%9D%E2%80%98%E2%80%99]))

No

At first glance IP address or URL, embedded in HTML, whatever it is, it's a doozy. I wonder what the performance of it is like.

Whatever this is supposed to match, I bet the bycatch is bigger than tuna fishing.

Looks like the hacking mini game in Fallout 4.

URLs in an HTML document that aren't namespaces or otherwise enclosed?

Hold on, let me draw up the NFA

:(

Probably documents from HP’s atrocious support site

Is it a rick roll?

www
urls