[TypeScript] can't reference D2RMM's own types in mods because the definitions are outside of the /mods/ folder

[Caedendi]

TypeScript support has been a blessing for my modding. One issue that I've run into a few times though is that D2RMM doesn't support its own types.

To reproduce, add this file to a mod and try to install it.

(Don't mind the technical side of what the code is supposed to do, it's still a work in progress)

import { JSONData } from "../../types"; // PROBLEM HERE

export class GameDataTest {
  protected skillsJsonFile: JSONData;

  constructor() {
    this.loadFiles();
    let row = this.findJsonFileEntryByKey(this.skillsJsonFile, "skillname59"); // blizzard
  }

  protected loadFiles(): void {
    this.skillsJsonFile = D2RMM.readJson(`global\\excel\\skills.json`);
  }


  protected findJsonFileEntryByKey(jsonFile: JSONData, key: string): Record<string, string> { // PROBLEM HERE
    let match = Object.entries(jsonFile).find(([_, value]) => value["key"] === key);
    return match ? { [match[0]]: match[1]["key"] } : {};
  }
}

D2RMM will give this error message:

[MOD NAME] Mod encountered a compile error!
Error: BridgeAPI.readModCode: Failed to compile mod: Error: BridgeAPI.readModCode: Failed to read mods\MODFOLDER\../../types.ts
    at I (C:\Users\Caedendi\Games\D2RMM\resources\app.asar\dist\main\worker.js:2:163626)
    at Object.readModCode (C:\Users\Caedendi\Games\D2RMM\resources\app.asar\dist\main\worker.js:2:174289)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async installMods (C:\Users\Caedendi\Games\D2RMM\resources\app.asar\dist\main\worker.js:2:176643)

[olegbl]

So, the way types.d.ts works is a bit magical in that any TS environment should automatically import the nearest types.d.ts up the directory structure without you having to specify it. So, you shouldn't ever need to import it manually like this.

[Caedendi]

Well I guess that seems to work, but it still leaves me with my IDE showing a lot of errors because it can't find those types. Is there a way to fix that?

[olegbl]

Oh, I think I understand your question - you want to reference the types in types.d.ts (such as JSONData) directly rather than just having D2RMM APIs be strongly typed. I think I'd just need to declare those types globally in types.d.ts.

[Caedendi]

Exactly, that's what I meant. For this line right here:

protected findJsonFileEntryByKey(jsonFile: JSONData, key: string): Record<string, string> { // PROBLEM HERE

So I can define param jsonFile to be of type JSONData without getting errors.

[olegbl]

BTW, until the exporting is done, you can always derive these types. e.g.:

type MethodReturn<TMethod> = TMethod extends (
  ...args: infer TArgs
) => infer TReturn
  ? TReturn
  : never;

type JSONData = MethodReturn<typeof D2RMM.readJson>;