Yes, Sapper is Node js “app lvl” framework from Svelte’s creator. There is also an Elder.js (a static site generator, but can be also used as Sapper) https://elderguide.com/tech/elderjs/ Btw how easy is to jump into Phoenix(and Elixir) as a JS dev?
Seriously tho, I think you will be fine. We see quite a few people come to Elixir and Phoenix from JS, in fact only yesterday the founder of http://www.scorebreak.io mentioned they moved over from Node
Just watched Svelte Summit, forget what I said about Sapper, it is now officially “dead” and will be replaced by another Svelte framework. We can assume that it will be the same Sapper, only better.
I’m not too sure what Sapper and this new framework is - a framework to make Svelte more like a frontend framework like Ember and Angular (so includes everything like a router, project structure etc) or a back end framework like Django or Rails tuned to work with Svelte? If the latter I would prefer they focus on Svelte itself tbh…
I see that Svelte will be more like Vue, that is, there will be an “official” way to create an app that will include router, SSR, etc, as well as a separate Svelte module as just a UI framework.
Therefore, if you want to use Svelte + Phoenix, then probably it will not differ in any way from what is already there.