Implement isNaN()

[TheSTL]

So you have to implement the isNaN()

Take care of:

• ESLint guidelines
• Filename convention

[jatin33]

Hi ,
Can I work on this issue?

[TheSTL]

Hi @jatin33
Yes can work on this issue.

[jatin33]

Hi @TheSTL ,

I have implemented the isNaN() function with required test cases and applied ESLint standards.
Please review my PR #33

Thanks in advance for reviewing PR.