Definition: isfinite is a global method that can be used to test for a number being too big for Javascript to handle. Unlike testing against Infinity directly which only allows you to test for a positive number overflow condition, using this method also tests for -Infinity. This is not a reserved word so you can declare your own variable or function called isfinite but if you do then you will not be able to use this method.
Examples:
if (isfinite(x))
