Please, help me understand why an answer is 1

Question

https://code.sololearn.com/W0YmfUw9srO2/?ref=app

Answer 1

== operator is not as strict as ===, maybe the == operator considers `undefined` as an equal to `null`. That is not the outcome of `j === null` on the `if` block.

Answer 2

This could give you some ideas about undefined and null.
https://stackoverflow.com/questions/5076944/what-is-the-difference-between-null-and-undefined-in-javascript

Answer 3

Thanks, I got it:)