Build: Deno is not defined

[ribizli]

I cannot use Deno API in +page.server.ts (probably also .js) files, because vite build ends with an error:

node:internal/event_target:1012
  process.nextTick(() => { throw err; });
                           ^
ReferenceError [Error]: Deno is not defined
    at file:///[...path removed for privacy...]/.svelte-kit/output/server/entries/pages/_page.server.ts.js:1:12
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25)
Emitted 'error' event on Worker instance at:
    at [kOnErrorMessage] (node:internal/worker:300:10)
    at [kOnMessage] (node:internal/worker:311:37)
    at MessagePort.<anonymous> (node:internal/worker:212:57)
    at [nodejs.internal.kHybridDispatch] (node:internal/event_target:737:20)
    at exports.emitMessage (node:internal/per_context/messageport:23:28)

Node.js v18.16.0

The error happens during or after "Analysing routes" step.

The +page.server.ts is something like this:

const kv = await Deno.openKv();

export async function load() {
    return {
        count: (await kv.get<number>(['count'])).value ?? 0
    };
}

[dbushell]

SvelteKit/vite uses Node for the build process so using Deno APIs isn't so easy.

This would technically work:

export async function load() {
  let count = 0;
  if ('Deno' in globalThis) {
    const kv = await Deno.openKv();
    count = (await kv.get<number>(['count'])).value ?? 0;
  }
  return {count};
}

I'm not sure I'd recommend this style for maintainability. At least create something like $lib/deno.js and keep all this logic in one place.

What I've done in production is have an entirely separate Deno server to handle data and provide API routes for SvelteKit.

[ribizli]

@dbushell thanks for the reply, I will go to this direction.

Maybe a last question: do you also experience a huge performance penalty when vite dev is started with deno?

[dbushell]

I've just been using Node for development

[ribizli]

ok, the whole idea to use KV came from your blog here: https://dbushell.com/2023/06/26/sveltekit-oauth-deno-deploy/.

but this is then just a theoretical possibility, not really a good practice, I see 😉

[dbushell]

I wouldn't say it's bad practice it's just that SvelteKit & vite are basically Node.js projects so using another runtime in development isn't easy.

This adapter is just for build/production runtime where Deno KV would be available. I don't have any solid advice on how to handle that during development!