More useful type definition

[lacolaco]

Currently, Comlink.proxy returns just Function type. It is not useful because any language services or editors cannot suggest await new Foo() interface.

My proposal is to define a type of Comlink.proxy function, called PromisedConstructor.

type Promised<T> = {
  [P in keyof T]: T[P] extends (...args: infer A) => infer R
  ? (...args: A) => Promise<R>
  : Promise<T[P]>
};
type PromisedConstructor<T>  = {
  new(...args: any): Promise<Promised<T>>;
};

TypeScript Playground

Usecase (w/ Angular)

import { Injectable } from '@angular/core';
import * as Comlink from 'comlinkjs';
type LoggerType = import('./logger').Logger; // import only types

type Promised<T> = {
  [P in keyof T]: T[P] extends (...args: infer A) => infer R
  ? (...args: A) => Promise<R>
  : Promise<T[P]>
};
type PromisedConstructor<T>  = {
  new(...args: any): Promise<Promised<T>>;
};

const LoggerProxy = Comlink.proxy(
  new (Worker as any)('./logger', { type: 'module' }) // global `Worker` workaround...
) as PromisedConstructor<LoggerType>;

@Injectable({
  providedIn: 'root'
})
export class LoggerService {
  async sendLog(value: any) {
    const logger = await new LoggerProxy(); // type safe
    await logger.log(value); // type-safe
  }
}

I've not found out yet how to extract the original constructor's arguments type. With the above type definition, await new LoggerProxy() 's constructor arguments are all recognized as any[].

Thanks.

[lacolaco]

Solved in v3.1. Thanks!