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isNaN function
isNaN(expression:Object) : Boolean
Evaluates the parameter and returns true if the value is NaN(not a number). This function is
useful for checking whether a mathematical expression evaluates successfully to a number.
Parameters
expression:Object - A Boolean, variable, or other expression to be evaluated.
Returns
Boolean - A Boolean value.
Example
The following code illustrates return values for the isNaN() function:
trace( isNaN("Tree") );
// returns true
trace( isNaN(56) );
// returns false
trace( isNaN(Number.POSITIVE_INFINITY) )
// returns false
The following example shows how you can use isNAN() to check whether a mathematical
expression contains an error:
var dividend:Number;
var divisor:Number;
divisor = 1;
trace( isNaN(dividend/divisor) );
// output: true
// The output is true because the variable dividend is undefined.
// Do not use isNAN() to check for division by 0 because it will return
false.
// A positive number divided by 0 equals Infinity
(Number.POSITIVE_INFINITY).
// A negative number divided by 0 equals -Infinity
(Number.NEGATIVE_INFINITY).
See also
NaN constant, NaN (Number.NaN property)
Global Functions 53