Method select

packages/core/src/createActor.ts:490–510

(
    selector: (snapshot: SnapshotFrom<TLogic>) => TSelected,
    equalityFn: (a: TSelected, b: TSelected) => boolean = Object.is
  )

  }

  public select<TSelected>(
    selector: (snapshot: SnapshotFrom<TLogic>) => TSelected,
    equalityFn: (a: TSelected, b: TSelected) => boolean = Object.is
  ): Readable<TSelected> {
    return {
      subscribe: (observerOrFn) => {
        const observer = toObserver(observerOrFn);
        const snapshot = this.getSnapshot();
        let previousSelected = selector(snapshot);

        return this.subscribe((snapshot) => {
          const nextSelected = selector(snapshot);
          if (!equalityFn(previousSelected, nextSelected)) {
            previousSelected = nextSelected;
            observer.next?.(nextSelected);
          }
        });
      },
      get: () => selector(this.getSnapshot())
    };
  }

  /** Starts the Actor from the initial state */
  public start(): this {