Validate is it a good date or invalid date?

Hello,

I have placed a DATE object field on my form, and did NOT placed any VALIDATION PATTERN, hence user can enter any data manually

But, bcz of some reason, we don't want to use VALIADATION PATTERN

But at the same time, we want to validate user entered data is a valid date or invalid date?

Pls. let me know the code snippet of JS or FormCalc, which validates whether its a valid date or not?

Thank you