Class TransferState

packages/core/src/transfer_state.ts:71–158

 * @publicApi
 */
export class TransferState {
  /** @nocollapse */
  static ɵprov = /** @pureOrBreakMyCode */ /* @__PURE__ */ ɵɵdefineInjectable({
    token: TransferState,
    providedIn: 'root',
    factory: () => {
      const transferState = new TransferState();
      if (typeof ngServerMode === 'undefined' || !ngServerMode) {
        transferState.store = retrieveTransferredState(inject(DOCUMENT), inject(APP_ID));
      }

      return transferState;
    },
  });

  /** @internal */
  store: Record<string, unknown | undefined> = createDictionary();

  private onSerializeCallbacks: {[k: string]: () => unknown | undefined} = createDictionary();

  /**
   * Get the value corresponding to a key. Return `defaultValue` if key is not found.
   */
  get<T>(key: StateKey<T>, defaultValue: T): T {
    if (!Object.hasOwn(this.store, key)) {
      return defaultValue;
    }

    const value = this.store[key];
    return value !== undefined ? (value as T) : defaultValue;
  }

  /**
   * Set the value corresponding to a key.
   */
  set<T>(key: StateKey<T>, value: T): void {
    this.store[key] = value;
  }

  /**
   * Remove a key from the store.
   */
  remove<T>(key: StateKey<T>): void {
    delete this.store[key];
  }

  /**
   * Test whether a key exists in the store.
   */
  hasKey<T>(key: StateKey<T>): boolean {
    return Object.hasOwn(this.store, key);
  }

  /**
   * Indicates whether the state is empty.
   */
  get isEmpty(): boolean {
    return Object.keys(this.store).length === 0;