finally a true 'best practice' solution!

Ah nevermind, I was actually not covering an edge case.

@dem4ron do you remember how you resolved it? I am getting the same error, even though it seems to work fine on an other IDE.

fun kata. I just don't understand why it is 6kyu and the other - simple result-checker kata - is 5 kyu. I think this kata looks a step further. It is fine for a 6kyu just I find the other one simpler. nvm

very fun kata! helped me to improve my debugging skills in CW:D

figured it out. probably the difference of node versions again...

now did the tests with the original input, just inserting my code, and the same error msg comes up. I am pretty sure I fuck up somewhere, but my test results are all the expected, so dont know how to debug..

Do you get the same error when running this test case locally in your IDE?

I modified the input field by creating a class, because it is simplier to me. could that cause the problem?

I am not sure what you exactly did, but remember that interface of your solution (name, parameters, return value) have to match to what tests expect because test suite calls your solution, so it has to know how.

in JS I passed 4 of 4 true and 6 of 6 false tests, but it gives the classic cannot read property 0 of undefined at... error.
I modified the input field by creating a class, because it is simplier to me. could that cause the problem? My code works with empty arrays and even without arrays..

thank you for your reply, sorry for wrong use of issue label.

Expected: '[\'a\', \'b\', \'c\', 1, \'1\', 2, \'2\', \'2\', 3, \'3\']', 
instead got: 
          '[\'a\', \'b\', \'c\', \'1\', 1, \'2\', 2, \'2\', 3, \'3\']'

Feedback is pretty clear here... Your chrome might be using different node version that handles sorting differently, IDK. I see in your code that your sort is incomplete, when elements are similar.

Anyway, your code not working is not a KATA issue! Please take your time to read this FAQ before raising issues.