JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
If I understand your requirement, you would like to show a warning message to the user if the difference between two data fields is less than 3.
Yes, that is possible. You can add a Calculation Field to calculate the date difference.
In the Calculation Wizard, you would need to add the ending date field minus the starting date field (marked 2 and 3 in the image below).
You would also need to click on Show advanced options (4) and make sure it is marked Read Only (5).
We would then add a condition using Conditional Logic, and set it so that it Show/Hide a form field and set it so that it displays the message when the day difference is less than 3.
Please take a look at the following demo form:
Please let us know if you need any help in setting this up, and we will be happy to assist you.