There is always an answer with JSF but it's not always as simple as it should be. Like validating (or not validating) a component could be a problem. Is it immediate ? Which form the component and the button is in ? Is ajax used ? You should consider these or your button may not work or the user may see unrelated validation messages.
I believe JSF is still good for apps where you need to process good amount of input from users, show some fancy ajax UI easily where otherwise you have to deal with JS.
The question is can't these all be simpler ?