very impressive. I did not think it was possible to avoid join, but you did it! well done.

it would be better to show actual, expected and diff tables for the better user experience. You could look at the other kata that povide such an info. e.g. this one

This is exclusively for PostgreSQL?

in JS message like

Testing for:
pros = ["pros-1","pros-2","pros-3","pros-4","pros-5","pros-7","pros-8","pros-10"]
preferences = [["Code progammer","Computer repair","Cook","Data recovery service","Haircut","Handyman","House cleaning","Pet care","President"],["Code progammer","Cook","Haircut","Handyman","House cleaning","President"],["Computer lessons","Computer repair","Cook","Data recovery service","Handyman","President"],["Computer repair","Data recovery service","Haircut","Handyman","Pet care","President"],["Code progammer","Computer repair","Cook","Data recovery service","Handyman","House cleaning","Pet care","President"],["Code progammer","Cook","Data recovery service","Haircut","Handyman","Pet care","President"],["Computer lessons","Pet care"],["Computer repair"]]: expected [ …(10) ] to deeply equal [ …(10) ]

isn't very useful. I see the input but almost no information about expected answer.
That's in Random tests

thanks!

You reached an epic milestone, congratz!

seems to work better now (anyway I fixed my solution before ;) )

should be fixed, please reset trainer and try again, or you will have a hard time reaching 2 dan in js ;)

in JS tests output is truncated like

Test failed for aroundFib(957): expected 'Last chunk 44842179940550505985582222…' to equal 'Last chunk 5402420264154456349058562;…'

so it is hard to debug

some names seem to be completely random, but there is some 'logic':

segments -> ss -> ß

result -> r

last -> l

help me get them out of beta, and you'll be rewarded 2 dan in javascript ;)