[mavbo]

Glad to see progress in this space.

I couldn't find anything describing the paradigm used for the JavaScript frontend. From the video, it looks like things are fully server side rendered, i.e. no client side routing as-in SvelteKit or Next.js? Are the Svelte components hydrated+interactive after page load? In my experience so far with SvelteKit and other SSR+SPA frameworks, there are too many tradeoffs with hydrating then opting to CSR for subsequent navigation. I like the browser's built-in implementation of navigating between pages because it preserves things like mutations to the document and scroll position out of the box, with no additional JavaScript. If you collapse a comment in this thread, navigate back to the home page, then use your browser's back button, the comment you collapsed should still be collapsed. In my experience with SPA CSR, you'll need to track and restore the JavaScript state driving that collapse on your own (a combination of the window.history object and CSR hooks), since navigating back to the page is a full client side re-render of the page.

I've found Svelte+React have good support for TypeScript, especially for guaranteeing the types of props passed to components, are there plans to support this? With controllers in Go and Views in Svelte/React, is there any way to help with correctness of data passed as props to the Svelte components?

[ammanley]

I only browsed for a wee bit, so take this with some salt, but it _looks_ like the framework is running a JS VM isolate alongside the Go server struct[1], which gets called with whatever script file is being rendered. Since it looks like the render files are, at least in the case of Svelte, individually compiled JS files that are SSR rendered via the V8 isolate, I _believe_ you're correct that there is no CSR (though there might still be JS-hydrated code if the Svelte component included something involving an interactive component).

I think the idea is to ingest a JS "template" and spit out the rendered HTML+JS, kind of like traditional SSR templates, but it could be possible to shoe-horn in an entire client-side router that gets initialized as a DOM object somewhere.

EDIT: I could be wrong, please correct me if so.

[1] https://github.com/rogchap/v8go

[matthewmueller]

Nice sleuthing! Bud heavily relies on https://github.com/rogchap/v8go

[c0balt]

Browsing the runtime/view/ssr source code it appears to use esbuild (over the VM?) for rendering the svelte views while injecting the relevant code etc.

[matthewmueller]

Hey, excellent question.

You're correct that Bud server-side renders the Svelte files, then hydrates them on the client.

This is similar to what most other JS frameworks do, it works like this:

1. Create two builds: one for server, one for browser. This is done using ESBuild. This is actually done lazily upon request, similar to how a CDN like esm.sh would build JS to be imported. This will hopefully allow the build system to scale for larger apps. Vite was my inspiration here, but it's all done in Go.

2. V8 and the Svelte compiler are baked into the bud binary. When a request comes in, V8 evaluates the compiler running the server-built page and returns HTML. That's a mouthful, hopefully that makes sense.

Happy to go into more depth here or via email [e-mail].

[matthewmueller]

I should add that lazy builds only happen in development. In production, it's all bundled at once.