All Primitive Values isFinite Function Math Object parseFloat Function parseInt Function FUNCTION:  isNaN isNaN(testvalue)   The isNaN function is used to determine if the argument, testvalue, is a NaN.   A NaN, which means "Not-a-Number", is classified as a primitive value by the ECMA-262 standard and indicates that the specified value is not a legal number. The function returns true if the argument is not a number and false if the argument is a number.   The classic example of a NaN is zero divided by zero, 0/0.   Code: document.write(isNaN("Ima String")) document.write(isNaN(0/0)) document.write(isNaN("348")) document.write(isNaN(348))   Output: true true false false Copyright 1999-2001 by Infinite Software Solutions, Inc. All rights reserved. Trademark Information