Select multiple values for frontend (and maybe backend)

Hello there,

I want to bring this kind of field to Frappe Doctypes to frontend (Web Forms) and maybe the Backend (in the Doc Forms):

https://www.w3schools.com/tags/tryit.asp?filename=tryhtml_select_multiple

At the moment the only way to do this, is to use child tables in the Backend. But for web forms, I didn’t find any solutions.

It should be easy to store the multiple values in the database, for example comma or semicolon separated. But where to start? EDIT: Probably it would be even better to store the values as JSON, because it might be easier to handle.

Any ideas?

What is the use case? Maybe just add the values in your form and push it to the other tables using a controller event.