* Indicates whether this subscription exceeded the background message quota,
   * or the user revoked the notification permission. The caller must request a
   * new subscription to continue receiving push messages.
   */
  isExpired() {
    return this.quota === 0;
  }

  /**
   * Returns a key for encrypting messages sent to this subscription. JS
   * callers receive the key buffer as a return value, while C++ callers
   * receive the key size and buffer as out parameters.
   */
  getKey(name) {
    switch (name) {
      case "p256dh":
        return this.#getRawKey(this.#props.p256dhKey);

      case "auth":
        return this.#getRawKey(this.#props.authenticationSecret);

      case "appServer":
        return this.#getRawKey(this.#props.appServerKey);
    }
    return [];
  }

  #getRawKey(key) {
    if (!key) {
      return [];
    }
    return new Uint8Array(key);
  }
}
PK