Steven Engelhardt

Be careful of the JavaScript parseInt() function. It treats numbers that start with "0" as octal and "0x" as hexadecimal, which may not be what you want if the user entered a month of "09". Furthermore, parseInt() will not throw an exception if the parameter is bogus (as "09" is) — it will return NaN.

Therefore, consider using the optional radix option to parseInt() and always check for NaN with isNaN().

I have some thoughts about the use of exceptions vs. return values to indicate errors that I may get to in a future post.