Thanks for the response and for the kata. I think this may because I'm new to Codewars and am still learning the flow. I hadn't seen a kata without premade sample tests before and had it in my head that passing the sample test was a prerequisite for attempting the kata, which looks to be wrong.

My impression of the test case comments was that it was default text provided by Codewars as instructions for the author to make sample tests--it didn't jump out to me as instructions from the author. I guess it may have been more clear to me if the instructions said "There may not be sample tests provided in your language for this kata, but the following are examples of expected output values: ..."

After failing for a while to figure out why this wouldn't pass my code on the sample tests, I gave up and looked at the other solutions. I tried a handful of the successful solutions to see if I was missing something, and the server always responded with the same error it threw on my code: "This is just an example of how you can write your own TDD tests - Expected: 'expected', instead got: 'actual'".

I think this is missing test cases for the JavaScript version.