boolean isFinite(number:number)
This function returns false if the argument coerces to NaN or infinity of any sign, true otherwise.
function isFinite(number){
var n = ToNumber(number);
if (isNaN(n) || n == Infinity || n == -Infinity) return false;
return true;
}
This function can not simply be used to test for infinity because it also returns false for NaN. This of course because if NaN is not a number, it's certainly not a finite number.