I've been tasked with building a component to allow the selection of some sane defaults or optionally allow the user to enter free text.
Semantic UI offers an Allow Additions option which enables the user to enter free text on a select drop down.
Is this optimal for usability and if so why?
My initial thoughts are this is too similar to a searchable dropdown. Would having a second input field help; Where the user explicitly selects Other in the dropdown and then a new input field is displayed. I don't know if I expect this behaviour from being trained by other forms. Is it bad usability to display new input based off current select?