Hello Geert,
Calculation fields can do a lot and are sufficient in many places.
Due to the highest possible security, the calculation becomes independent of each other
- a first time locally in the browser in JavaScript and
- done a second time in PHP in the backend.
However, this results in an intersection of the available functions and actions that you can use.
Because the code must be executable for JavaScript and PHP at the same time.
In your case, it is better if you implement your individual solution with JavaScript and the 'Visforms web assets'.
Here you have virtually all the options you need.
You can react (a field value changes), calculate and act as you wish (influence other fields).
You simply add your JavaScript code to the affected Visforms view (form, data, ...) using the Visforms 'Frontend Webassets'.
The procedure is described in the documentation.
Frontend web assets:
docs.joomla-5.visforms.vi-solutions.de/e...-frontend-webassets/
All settings are made in the form:
docs.joomla-5.visforms.vi-solutions.de/e...are-made-in-the-form
Examples of solving requirements with the frontend web assets:
docs.joomla-5.visforms.vi-solutions.de/e...-webassets/examples/
Kind regards, Ingmar