I needed a method that would validate dates in multiple formats. Here are examples of dates that needed to pass validation: ‘6/9/2021’, ‘6/10/2021’, ‘9-Jun-2021′, ’10-Jun-2021′, ’06/09/2021′, ’06/10/2021’. This problem came to me on June 9th, 2021. So ’06/09/2021′ failed, but ’06/10/2021′ passed. Hmm… If you guessed it was not allowing backdates, you’d be wrong.

In my testing I learned that typeof 09 == ‘number’, but parseInt(09) = NaN. How can that be?

The NetSuite (server-side) JavaScript engine treats numbers with leading zeros as base-8 (octal). So be sure to strip leading zeros, even on integer numbers of type ‘number’. Since base-8 only included digits 0 through 7, parseInt(09) is not a number!