Improve description of Number.isNaN()

[gevuong]

MDN URL

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isNaN

What specific section or headline is this issue about?

The second part of the first sentence in the page.

What information was incorrect, unhelpful, or incomplete?

The first sentence states the following: The Number.isNaN() static method determines whether the passed value is the number value NaN, and returns false if the input is not of the Number type.

I think the second part of the sentence, and returns false if the input is not of the Number type, may be inaccurate (or confusing) because:

1. NaN is considered a Number type when checking its type using typeof.
2. Therefore, passing NaN as the input would return true, not false.

What did you expect to see?

I think I expected to see something like, The Number.isNaN() static method determines whether the passed value is the number value NaN, and returns false if the input is not NaN.

Do you have any supporting links, references, or citations?

No response

Do you have anything more you want to share?

No response

[Josh-Cena]

The first half of the sentence already covers everything "The Number.isNaN() static method determines whether the passed value is the number value NaN". The second half is only added to distinguish from isNaN(), which may return true for non-number inputs. The current text is not wrong—it does return true only if the input is NaN; it always returns false if the input is non-number.

[gevuong]

Oh right, I see. Sorry, I misunderstood the statement 😅

[gevuong]

After reviewing it once more, I think I understand why I was confused.

I misunderstood the second half, and returns false if the input is not of the Number type, and thought Number.isNaN() returns false only if the input is a non-number type. But that's not true. An input can be a number type and still return false (ie. Number.isNaN(5)).

With your explanation of why the second half was added, to distinguish from isNaN() which can return true for non-number inputs, it made more sense. Thanks for the clarification.