Thank you for your prompt reply ... I tried the code, everything seems correct, via "console.log" I see correct values, the field doesn't change until a "human" enter value manually in the field.
I think I understood the example of codepen:
and it works, but in squarespace form it doesn't. Any ideas?
At least, what I'm trying to do is simply trap 2 additional controls in a form, for example: range of dates, range of hours. I'm not able to "prevent" the form submission in any way (button is not "prevantable"), so I was trying to have a hidden field mandatory, to fill with a value only when my custom controls are ok. That's quite simple, but squarespace doesn't permit me to customify almost nothing 😞
If you have any ideas and / or advices i would appreciate very much.