You could implement an upvote or like as a hyperlink or a form, then progressively enhance that feature to not initiate a full page reload (iirc this is how HN implements upvotes). Similarly expanding or collapsing an accordion menu could be a hyperlink which by default does request the additional content but which can be progressively enhanced to provide that feature with JavaScript for user agents that support it. As an added benefit to supporting more clients, I find it easier to reason about the state of the view when it is encoded entirely in the URL, and available state transitions being to be encoded using features of well known media types like html. This is one of the main benefits of REST: any user or user-agent which knows the media type knows how to interact with the application.
It makes some sense to have an upvote be a form that posts somewhere and the response of which is a redirect (maybe a 307?) back to the page you’re on and then the progressive JavaScript enhancement would be to perform the request asynchronously instead of redirecting.
It makes sense because adding an upvote is the same as adding other form data to a database semantically so really should be treated the same way.
