Date Validation

[wxdqz]

I am looking to simply validate if a future date enterred is less than 30 days from the current date. If the user enters a date that is less than 30 days from today for example, an alert will pop up with a message. I was unsure if this had to be done using Julian dates or not. Does anyone have an example of code doing a check like this.

Format of user input is mm/dd/yyyy


Thanks!