I'm using the 'Join User Group' addon to allow my forum members to join a NSFW (not-safe-for-work) subforum. I like the option of a checkbox in the user's account section, which seems quite nice.
However, I'd like to make a standalone webpage where users can click a button, and be opted in. To clarify, I'm going to make a warning page that warns the user that they're entering the NSFW (18+) subforum, and will need to opt-in in order to see it. How can I make a button that will add them to the user group?
If you can share some snippets of code, that would really help