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isNaN Method (JScript 5.6) 

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Returns a Boolean value that indicates whether a value is the reserved value NaN (not a number).


isNaN(numValue)

Return Value

true if the value converted to the Number type is the NaN, otherwise false.

Remarks

The required numValue is the value to be tested against NAN*.*

You typically use this method to test return values from the parseInt and parseFloat methods.

Alternatively, a variable 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

Version 1

Applies To: Global Object (JScript 5.6)

Example

isNaN(100);                   //Returns false

isNaN("100");                 //Returns false

isNaN("ABC");                 //Returns true

isNaN("10C");                 //Returns true

isNaN(Math.sqrt(-1));         //Returns true

See Also

Reference

isFinite Method (JScript 5.6)
NaN Property (Global) (JScript 5.6)
parseFloat Method (JScript 5.6)
parseInt Method (JScript 5.6)