Kacaii•3mo ago

Workers: Property 'onmessage' dos not exist

Im learning how to create worker threads but deno-ts says: Property 'onmessage' does not exist on type 'Window & typeof globalThis'. Code

// worker.ts
self.onmessage = (message) => {
  // TODO: Do something with the message?
};

// worker.ts
self.onmessage = (message) => {
  // TODO: Do something with the message?
};

Am I missing some configuration?

7 Replies

ud2•3mo ago

Add these lines to the top of worker.ts.

/// <reference no-default-lib="true" />
/// <reference lib="deno.worker" />

/// <reference no-default-lib="true" />
/// <reference lib="deno.worker" />

And if you run deno check as part of your workflow, instead of deno check main.ts worker.ts, do deno check main.ts and deno check worker.ts separately, or there may be false negatives.

KacaiiOP•3mo ago

Thank you! Also, in what part of the documentation I can search to learn more about those top level comments?

ud2•3mo ago

These are triple-slash directives. no-default-lib="true" means “don't include default libraries” (deno.window and deno.unstable in Deno's case), and lib="…" references the specified library. I just read that no-default-lib might get deprecated soon. If that happens, the alternative would be to set compilerOptions.lib to [] in deno.json, and add a reference to deno.window to all non-worker scripts.

Doctor 🤖•3mo ago

I know of a package that makes using workers easier, but it is a bit of self advertisement. 😛

ElectronicFreezer•3mo ago

im curious its also possible to do export const self = globalThis as unknown as Worker and then import self in workers but maybe a little cursed

Doctor 🤖•3mo ago

https://jsr.io/@doctor/thread

JSR

@doctor/thread - JSR

@doctor/thread on JSR: A wrapper API around the Web Worker API

Doctor 🤖•3mo ago

It's going to receive better typings soon™️

Workers: Property 'onmessage' dos not exist

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