Calculating using dates...creating varibles with dates?

Any date calculations would need to be done with javascript, slide 2.2 has an age calculator

So I have two questions i'm trying to answer and calculate.
1. What is the date of birth for your pet?
2. When was it vaccinated?

The calculation should give you and answer saying yes your in compliance or
no. Can I do something that specific before I waste my time trying to
figure out the code for it?

Thanks, you're always a great help.

Cindy