FUNCTION: isNaN (Java Script)

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")) // true

document.write(isNaN(0/0)) // true

document.write(isNaN("348")) // false

document.write(isNaN(348)) // false