If the form need to validate start and end date, you should take a look at the Validating fields that depend on each other or Compraing dates example.
This document was produced by a group operating under the 5 February 2004 maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent.
An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the is data that is structured into rows, each of which contains information about some thing.
For example, 41/01/2001 is not a real date, despite it being in the correct format.
Folks on the forum may (rightfully) suggest looking at other PDI Steps to help with date validation before trying Java Script Step.
Outgoing Stream On Error from Select Values, send to Set Field Value (set the field to null) and then redirect it back into the Outgoing Steam.