javascript math.isnan

 Number.isNaN() is a method used to determine whether a value is NaN (Not-a-Number) and is of type number. 

It is different from the global isNaN() function in that it does not coerce the value to a number before testing it. 

This means that Number.isNaN() is a more reliable way to test specifically for NaN values.

Syntax

Number.isNaN(value)

• value: The value to test.

Returns

• true if the value is NaN and is of type number.
• false otherwise.

Differences from isNaN()

• Number.isNaN() checks if a value is exactly NaN.
• isNaN() coerces the value to a number before checking, which can lead to unexpected results.

Examples

Here are 10 examples demonstrating how Number.isNaN() works:

1. Basic NaN Check

   
   console.log(Number.isNaN(NaN)); // true
   

2. Number that is not NaN

   
   console.log(Number.isNaN(123)); // false
   

3. String that is not NaN

   
   console.log(Number.isNaN('hello')); // false
   

4. Number object with NaN value

   
   let numObj = new Number(NaN);
   console.log(Number.isNaN(numObj)); // false
   

5. Infinity (Positive)

   
   console.log(Number.isNaN(Infinity)); // false
   

6. Infinity (Negative)

   
   console.log(Number.isNaN(-Infinity)); // false
   

7. NaN from arithmetic operation

   
   let result = 0 / 0;
   console.log(Number.isNaN(result)); // true
   

8. Boolean value

   
   console.log(Number.isNaN(true)); // false
   console.log(Number.isNaN(false)); // false
   

9. Null value

   
   console.log(Number.isNaN(null)); // false
   

10. Array containing NaN

    
    let array = [NaN];
    console.log(Number.isNaN(array[0])); // true
    

Key Points

• NaN is a special value in JavaScript that stands for "Not-a-Number" and is a member of the number type.
• Number.isNaN() is more precise for checking NaN values compared to the global isNaN(), which can produce unexpected results due to type coercion.