Comment by dvdkon
1 hour ago
Not always. Consider an SPA that connects via WebSockets and streams in data, adding points to a chart. The JS-less alternative would be refreshing an SVG or even the whole page once a second. The SPA is clearly more efficient here (unless someone screws it up badly).
I wouldn't consider that an SPA at all, it's just a page with an interactive element. An SPA is something that renders everything client-side and uses a generic client API to talk to the backend. A telltale sign of an SPA is that the first thing you see when you open it is some sort of loading indicator instead of the actual page you're visiting.