isNaN Method
Returns a Boolean value that indicates whether a value is the reserved value NaN (not a number).
function isNaN(number : Number) : Boolean
Arguments
- number
Required. A numeric value.
Remarks
The isNaN function returns true if the value is NaN, and false otherwise. You typically use this function to test return values from the parseInt and parseFloat methods.
Alternatively, a variable that contains NaN or another value could be compared to itself. If it compares as unequal, it is NaN. This is because NaN is the only value that is not equal to itself.
Requirements
Applies To:
Example
// Returns false.
isNaN(100);
// Returns false.
isNaN("100");
// Returns true.
isNaN("ABC");
// Returns true.
isNaN("10C");
// Returns true.
isNaN(Math.sqrt(-1));