API Reference

DeepAsync

type DeepAsync<TService> = TService extends (...args: any) => any
  ? ToAsyncFunction<TService>
  : TService extends { [key: string]: any }
    ? {
        [fn in keyof TService]: DeepAsync<TService[fn]>;
      }
    : never;

A recursive type that deeply converts all methods in TService to be async.

defineProxyService

function defineProxyService<TService extends Service, TArgs extends any[]>(
  name: string,
  init: (...args: TArgs) => TService,
  config?: ProxyServiceConfig,
): [
  registerService: (...args: TArgs) => TService,
  getService: () => ProxyService<TService>,
] {
  // ...
}

Utility for creating a service whose functions are executed in the background script regardless of the JS context the they are called from.

Parameters

• name: string
  A unique name for the service. Used to identify which service is being executed.
• init: (...args: TArgs) => TService
  A function that returns your real service implementation. If args are listed, registerService will require the same set of arguments.
• config?: ProxyServiceConfig

Returns

• registerService: Used to register your service in the background
• getService: Used to get an instance of the service anywhere in the extension.

flattenPromise

function flattenPromise<T>(promise: Promise<T>): DeepAsync<T> {
  // ...
}

Given a promise of a variable, return a proxy to that awaits the promise internally so you don't have to call await twice.

This can be used to simplify handling Promise<Dependency> passed in your services.

Examples

function createService(dependencyPromise: Promise<SomeDependency>) {
  const dependency = flattenPromise(dependencyPromise);

  return {
    doSomething() {
      await dependency.someAsyncWork();
      // Instead of `await (await dependencyPromise).someAsyncWork();`
    }
  }
}

ProxyService

type ProxyService<TService> =
  TService extends DeepAsync<TService> ? TService : DeepAsync<TService>;

A type that ensures a service has only async methods.

• If all methods are async, it returns the original type.
• If the service has non-async methods, it returns a DeepAsync of the service.

ProxyServiceConfig

interface ProxyServiceConfig extends ExtensionMessagingConfig {}

Configure a proxy service's behavior. It uses @webext-core/messaging internally, so any config from ExtensionMessagingConfig can be passed as well.

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