NaN in JavaScript (Not-A-Number)

The NaN global property in JavaScript represents a value that is "Not-A-Number." While NaN is classified as a number, it signifies that the value it represents is not a valid number.

What is NaN?

• Definition: NaN stands for "Not-A-Number."

• Purpose: It indicates that a calculation did not yield a valid numerical result.

For instance, during a calculation, if an invalid number is generated, JavaScript represents it using NaN.

Example: Invalid Number

let result = 0 / 0;
console.log(result); // Output: NaN

Here, dividing 0 by 0 produces an invalid result, represented by NaN.

Key Characteristics of NaN

1. NaN is a Number: While NaN stands for "Not-A-Number," it is still categorized as a number in JavaScript.

2. Invalid Representation: NaN indicates a value that cannot be represented as a valid number.

Valid Numbers

Here are examples of valid numbers:

console.log(1);   // Output: 1
console.log(2);   // Output: 2
console.log(2.5); // Output: 2.5

In contrast, the following is an example of an invalid number:

let invalidNumber = 0 / 0;
console.log(invalidNumber); // Output: NaN

In this case, while NaN is technically a number, it does not represent a valid numerical value.

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Operations with NaN

You can perform operations involving NaN, but the results will also be invalid (NaN).

Example

let invalidOperation = NaN + 5;
console.log(invalidOperation); // Output: NaN

Why?

Any operation with NaN results in NaN because the original value is not valid. For instance:

let invalidAddition = NaN + NaN;
console.log(invalidAddition); // Output: NaN

let invalidMultiplication = NaN * 2;
console.log(invalidMultiplication); // Output: NaN