In magento 2 what is $F in js.phtml file

Question

Please open file "vendor\magento\module-catalog\view\adminhtml\templates\catalog\product\attribute\js.phtml".

Go to the function updateRequriedOptions(Line Number 258)

 function updateRequriedOptions()
{
    if ($F('frontend_input')=='select' && $F('is_required')==1) {
        $('option-count-check').addClassName('required-options-count');
    } else {
        $('option-count-check').removeClassName('required-options-count');
    }
}

Please, what is $F here?

Answer 1

According to prototype documentation

$F(element)

Returns the value of a form control. This is a convenience alias of Form.Element.getValue

Check Documentation