It is not stated anywhere in the description that you can't reuse letters. If you look at the author's solution, his solution would also "fail" the test you put.

Test.assertEquals(countFeelings('desir', ['desire', 'joy', 'shame', 'longing', 'fear']), '0 feelings.');
This solutions will fail this test.

Heh, nice trick with the 'constructor'. Codewars makes me too complacent just using truthy/falsy values.

Fixed the random tests ( reference solution was sorting inputs ). If you pass the random tests by chance, enjoy the cheap points.

the most clever !

This made me laugh. Have my vote.

This should probably be a 6kyu, nice kata though.

This is a bit tricky for a 6kyu, I'd probably label it as 5kyu

I feel like test cases should also be testing strings like "5", there's some solutions that wouldn't pass if that was the case.

The tests cases don't test for this case but your solution wouldn't work if x was something like "5"

STRANGE_STRING.length === 80085

Just so you know, this doesn't work for all test cases, you got lucky you didn't get a failed test case in a random test. Here's an example where it returns true when it should be false: 854658

BEST SOLUTION EVER

1. Not without transforming the list into a random access structure
2. This is one loop. The sum of the two loops will run over the list exactly once.

Nice ( • )( • )