Would benefit from not asking for a function, but for a regex, that is then used in "$something".replace( $yourRegex, $something ) somehow. I don't see how you'd replace domain.tld to codewars.com and return a regex though.

Maybe have us write a regex that matches the wanted string ( starting with /, not ending in /, otherwise unchanged ), with a subexpression match for "domain.tld" ( which can vary ).

Anyhoo, this is not it.

Only one test?!

No random tests.

No sample tests.