Thank you for your description. Very helpful !!!

Thanks for sharing this, definitely helped me!

That is an example on how to write your own tests. You have to do it yourself or directly press submit.

Your function needs at least one return line but you can use as many console.log as you need to debug your code.

Already told you how to debug your code, have you tried? Use console.log(arr) after you filled it, your problem will become evident.

It should work, just don't remove your return statement to console.log.
Logging is for debugging, you still need to return your final value.

It's a problem with your code, use console.log to print the arrays you use.
And next time, mark your post as having spoiler content.