for loop code is returning me undefined.

Question

My For Loop Code is returning me undefined for some reason I don't know at all. I know I am doing something wrong here. So, Please help me and please me an explanation too.
https://code.sololearn.com/W50pjES7J2Wr/?ref=app

Answer 1

Array Index starts from 0 so max index is array.length-1
So use condition a<num.length instead of a<=num.length

Answer 2

Thanks it's solved now.