Is NaN Method

The Is NaN method determines if the value that the value argument contains is a number. It returns one of the following values:

• The value is a number. It returns the following value:

  True

• The value is not a number. It returns the following value:

  False

If the value argument references an object, then the Is NaN method always returns true because an object reference is not a number. For more information on the number object, see NaN Numbers.

Format

isNaN(value)

The following table describes the arguments for the Is NaN method.

Argument	Description
value	The variable or expression that this method evaluates.

Example

The following examples use the Is NaN method:

IsNaN("123abc") //returns true
IsNaN("123") //returns false
IsNaN("999888777123") //returns false
IsNaN("The answer is 42") //returns true

For more information, see Is Finite Method.