I found this article (http://www.developertutorials.com/tutorials/javascript/javascript-form-submission-no-button-050412-1292/), but it is 8 years old (c. 96 in Internet and duckbilled Platypus years).
strager's answer here: Submitting a form by pressing enter without a submit button indicates that it might be as easy as calling "this.form.submit();" in a selection's event (onChanged() or whatever).
Is that so? Or not so? Or so not so?