Is Number Isnan More Broken Than Isnan

Before delving into the comparison of two vital functions in JavaScript, `isNaN` and `Number.isNaN`, it's essential to understand what they are and their significance in coding. Both functions are used to check whether a value is NaN (Not-A-Number) or not in JavaScript.

The traditional `isNaN` function is often used to determine if a value is considered NaN. However, it has some limitations and quirks that can lead to unexpected results. One of its major flaws is that it coerces non-number values into numbers before performing the check. This behavior can sometimes be counterintuitive and may not give the expected results.

On the other hand, `Number.isNaN` is a newer addition to JavaScript that provides a more robust and reliable way to check for NaN values. It explicitly checks whether a value is of the type `Number` and NaN, without any type coercion. This means that it only returns true if the provided value is of the type Number and NaN, making it a more precise and reliable option for detecting NaN values.

To illustrate the difference between the two functions, consider the following examples:

isNaN('hello'); // true
Number.isNaN('hello'); // false

In the first example, the `isNaN` function incorrectly returns true because it coerces the string 'hello' into a number, resulting in NaN. On the other hand, `Number.isNaN` accurately identifies that the string 'hello' is not a valid Number type with NaN value and returns false.

Another important distinction between the two functions is how they handle non-numeric values:

isNaN(undefined); // true
Number.isNaN(undefined); // false

In this case, `isNaN` returns true because it coerces `undefined` into NaN as a non-numeric value, while `Number.isNaN` correctly identifies `undefined` as not a valid Number type with NaN value and returns false.

Overall, while both `isNaN` and `Number.isNaN` serve the purpose of detecting NaN values in JavaScript, `Number.isNaN` is generally considered more reliable and less prone to unexpected behavior due to its strict type checking. If you want precise results without type coercion quirks, it's recommended to use `Number.isNaN` over the traditional `isNaN` function.

In conclusion, understanding the differences between `isNaN` and `Number.isNaN` can help you write more robust and predictable code when checking for NaN values in JavaScript. By leveraging the strengths of `Number.isNaN`, you can avoid potential pitfalls and ensure your code behaves as expected in various scenarios.