It's regular expressions, they are not supposed to be readable. It's a great tool that you shouldn't avoid just because it doesn't look pretty.

I guess so, but this isn't really regex so it doesn't follow the premise of the kata.

Agreed... definitely not best practices haha. As Voile said though it's a RegEx issue, not a JS issue.

To be fair, it has nothing to do with JS but has to do with regexes. There's another kata of the same task (but in C#) and it's still the same kind of mess.

don't hate the player hate the game...

This one is almost as short as the one line answer but you have code and it is easy to read and understand.
This is a lot more best practice than the one line answer.

Best Practice? it is completely unreadable
may be it is the shortest one but show it to anyone non JSfluent to see if they understand it