Support for compile-to-JS languages?

[spiffytech]

Can Svelte be used with compile-to-JS languages, like TypeScript and ClojureScript? How can I tell Svelte to look for behaviors in my generated code?

[Rich-Harris]

No reason this wouldn't work – as long as Svelte takes delivery of ES<=2017 that adheres to the component spec, it'll take it from there. So you would just need to preprocess your TypeScript accordingly.

Eventually it'd be nice to allow pluggable transpilers a la vue-loader, but it's probably a ways down the priority list tbh.

[spiffytech]

#65 sounds like Svelte won't load external .js files - like it requires behaviors to be specified inside a script tag in the template file. And that at this time there's no ready-made tooling to inject .js files into a template. Is that correct? Is that the expected way to deliver the TypeScript output to Svelte?

[Rich-Harris]

@spiffytech For now, yes – you'd need to glue the code together before passing it to Svelte, until #65 is implemented.

[Datamance]

Could you support this how handlebars does it - with the type attribute of the script tag?

[Conduitry]

Closing this since we have svelte.preprocess. If someone disagrees, we can reopen.

[jaccarmac]

Is this essentially dead given the changes in Svelte 3 or is there some programmatic way to hook into the compiler? I've been playing with various approaches to integrating shadow-cljs, but the new syntax introduced to Svelte seems to be a wall.

[TehShrike]

@jaccarmac preprocess support was added back in Svelte 2, and is still around in Svelte 3.

[jaccarmac]

CLJS is something of a special case given the Closure integration and the necessity of implementing sugar for things like $:. (Unless there's a non-sugared syntax in Svelte for the like. Haven't yet taken a deep look at the compiler source.)

[jaccarmac]

No reason this wouldn't work – as long as Svelte takes delivery of ES<=2017 that adheres to the component spec, it'll take it from there.

Specifically, this seems to no longer be the case.

[TehShrike]

Are you saying that you're using a language that doesn't give you a way to generate JS labels?

That seems like a separate issue from this general "support compile-to-JS transforms" issue.

You could bring up specific details in the Discord chat if you want to look for some help brainstorming?

[jaccarmac]

Had not realized $ was a valid label (or remembered that JS had labels), thanks! Emitting arbitrary JS isn't something I know how to do in CLJS but that makes things significantly simpler. I'll take further discussion to the Discord indeed.

[seanthingee]

Are there any updates on this topic? I'm curious about integrating Clojurescript as well.