Also: in your case, the model (pages in your site, content in the tabs) isn't changing, the view is, and the built-in capabilities of the browser as the "contro

Also: in your case, the model (pages in your site, content in the tabs) isn't changing, the view is, and the built-in capabilities of the browser as the "controller" are sufficient for a static model. Reacting to a user event doesn't mean it's a "reactive UI", every UI is a reactive one by that definition.