compared to other kyu 8 katas this one is harder. It could be kyu 7

dragon mage has a bot for his honor ban him pls

nice

hello, unfortunately kata ranks cannot currently be changed on Codewars

In my opinion, this should be re-rated as 7kyu. While the concept is simple, the requirement to simultaneously handle null/undefined inputs, empty strings, and forced case-normalization (lowercase-to-uppercase and vice versa) requires more logical steps than a standard 8kyu 'entry-level' challenge. It’s a great exercise in string manipulation, but the complexity of the edge cases definitely leans toward 7kyu territory.

Münda ağylshyn tilinen basqa til qabyldanbaidy. Sondyqtan, özbek kommentterdi jazbaiyq.

If you have a question, you could use the question tag.

I could tell you work with JavaScript, but you should always state the language you are using.

It would also be helpful to show the error message you're getting:

TypeError: Cannot read property 'toLowerCase' of undefined

Your code gets this because it is trying to use .toLowerCase() on an object that is not a string.

Check the sample test inputs, and perhaps use a type-check on any input sent into your funbction.

Your question is not clear

i dont underestand it says dont underestand toLowerCase() method so how can i say it?

This is causing the test to fail regardless of the learner's code.

No, there is a way to make your code accept no argument.

Approved.

Groovy Translation

.

You need to make your code work when called like hello("bob") or when it's just called as hello(). You should be able to call your function with either 1 or 0 arguments. Your code only works when it is called with 1 argument.