NaN

NaN in JavaScript

NaN is a value that represents "Not a Number".

Generally found in an illegal operation on numbers or trying to perform an operation on non-numeric data types.

It is of type Number:

> typeof NaN
= 'number'

NaN is common when:

• Trying to divide by zero
• Find the square root of negative number
• Trying to convert a non-number value to a number

NaN is the only JavaScript value not equal to itself.

> let value = NaN;
> value === NaN         // We'll talk about this in a few minutes
= false

> NaN === NaN
= false

To determine if a value is NaN, use one of the two following methods:

> let value = NaN;
> Number.isNaN(value)
= true

> Object.is(value, NaN)
= true