ActionScript for Flash MX: The Definitive Guide, 2nd Edition By Colin Moock
Chapter 18. ActionScript Language Reference
isFinite( ) Global Function
Flash 5
check if a number is less than Infinity and greater than -Infinity
isFinite(number)
Arguments
number
Any numeric value or expression that yields a numeric value.
Returns
The Boolean true if the number falls between -Number.MAX_VALUE and Number.MAX_VALUE (inclusive); otherwise, false. If number does not belong to the number datatype, number is converted to the number type before isFinite( ) executes.
Description
The isFinite( ) function simply checks if a number is in the legal numeric value range of ActionScript. It is equivalent to checking whether number is a number less than Infinity and greater than -Infinity. Use isFinite( ) before executing code that requires a legitimate number to operate properly.
Example
if (!isFinite(x * y)) { // Test if the number is not finite trace("The answer is too large to display. Try again."); } isFinite(-2342434); // Yields true isFinite(Math.PI); // Yields true isFinite(Infinity) // Yields false isFinite(-Infinity) // Yields false isFinite(NaN) // Yields false