[SOLVED] Can somebody help me?

Question

https://code.sololearn.com/WABwfUOE9WGR/?ref=app
How is it possible?
The last line should have been false!
It's a challenge question

Answer 1

🚩राजाबाबू शाह🇮🇳 Thank you 👏👏👍👍

Answer 2

🚩राजाबाबू शाह🇮🇳 Thank youu
But why?
isNaN(undefined) gives true?
One more doubt!
Why isNaN('abc') giving true?
is that because it should be a single character due to single quotes?