Form -> Hidden Field?

Does Webix Form support Hidden Field?

Not a “Hidden” property, but form field “Hidden”, where I can store hidden data and send data of this field with form submit.

There is no “hidden” field as separate entity

When you are using form.setValues ( or any other way to load a data in the form ) form will preserve all values - you can think about it as automatic hidden inputs. That data will be available through getValues and will be sent to server side during data saving.

So, if I use:

$$(‘my_form’).setValues({ field_b:“Paris” });

and “field_b” as a field does not exist on a form as an UI element, I still will be able to write data into and read from this field?

Yes
The getValues call will return { field_b:“Paris” }
Also, you can update any hidden value in form without affecting any other values like next

form.setValue({ field_b: "New value"}, true)