Array : Why is my recursive function returning undefined?

Array : Why is my recursive function returning undefined?
To Access My Live Chat Page,
On Google, Search for "hows tech developer connect"

I promised to reveal a secret feature to you, and now it's time to share it.
This is a YouTube's feature which works on Desktop.
First, Make sure this video is playing.
After that, type the word 'awesome' on your keyboard.
It will change your youtube progress bar into a flashing rainbow.

Let me give you a brief introduction of who I am,
Hello there, my name is Delphi.
I am here to help you get the answers you are seeking.
Array : Why is my recursive function returning undefined?
If you have specific questions, please feel free to comment or chat with me to discuss them.
If you have an answer or any relevant information to share, please comment below.
Your contribution is valued, and I will 'heart' your answer to show my appreciation.
returning is : recursive function Array Why undefined? my