What is the purpose of the `isNaN()` function?
The isNaN() function is used to determine whether a value is NaN (Not-a-Number) or not. It returns true if the value is not a valid number; otherwise, it returns false.
The isNaN() function is used to determine whether a value is NaN (Not-a-Number) or not. It returns true if the value is not a valid number; otherwise, it returns false.