[Bug]: emitDecoratorMetadata not respected in Deno Deploy

[cleverplatypus]

Problem description

While experimentalDecorators setting in deno.json is now respected since denoland/deno#22521
emitDecoratorMetadata is not. Unlike the former issue, it doesn't seem to be an issue with deno compile. In fact, compiled deno apps work as expected locally.

This issue makes decorator-based dependency injection not viable in deno apps in Deploy.

Steps to reproduce

deno.json

{
    "compilerOptions": {
        "experimentalDecorators": true,
        "emitDecoratorMetadata": true
    }
}

server.ts

import { Reflect } from 'https://deno.land/x/[email protected]/mod.ts';

export type ClassConstructor<T = unknown> = new (...args: any[]) => T;

function Annotation<T>() {
  return (_: ClassConstructor<T>): void => {};
}

class Custom {

}

@Annotation()
class Test {
  constructor(name: string, age: number, custom : Custom) {}
}

Deno.serve((_request: Request) => {
  const metadata = Reflect.getMetadata('design:paramtypes', Test);
  
  return new Response(metadata?.map((x: ClassConstructor) => x.name).join(', ') || 'No metadata. But it should output "String, Number, Custom"');
});

Expected behavior

Classes annotated with TC39 decorators should emit metadata that should be made available in design:paramtypes.

Environment

works in this environment

deno 1.41.1 (release, x86_64-apple-darwin)
v8 12.1.285.27
typescript 5.3.3

doesn't work in

Deno Deploy (as of March 10th 2024)

Possible solution

No response

Additional context

No response

[cleverplatypus]

@bartlomieju No feedback yet?

[dirkluijk]

Not sure if this is any help, but I've been working on a new dependency injection library for JavaScript that does not rely on experimentalDecorators or emitDecoratorMetadata, but solely uses stage 3 class decorators that work fine with Deno.

Not trying to advertise (it's a non-profit open-source project anyway), but just to mention alternatives that work well on Bun.

[thomas3577]

Not sure if this is any help, but I've been working on a new dependency injection library for JavaScript that does not rely on experimentalDecorators or emitDecoratorMetadata, but solely uses stage 3 class decorators that work fine with Deno.

Not trying to advertise (it's a non-profit open-source project anyway), but just to mention alternatives that work well on Bun.

Oh, that looks very good. I'm going to try your library.