财产申报！在打字稿课上

Question

我现在正在使用JHipster，它会自动在打字稿中生成前端代码。 这是我现在正在阅读的代码：

@Component({
  selector: 'jhi-user-mgmt',
  templateUrl: './user-management.component.html'
})
export class UserManagementComponent implements OnInit, OnDestroy {
  currentAccount: Account | null = null;
  users: User[] | null = null;
  userListSubscription?: Subscription;
  totalItems = 0;
  itemsPerPage = ITEMS_PER_PAGE;
  page!: number;
  predicate!: string;
  previousPage!: number;
  ascending!: boolean;

  constructor(
    private userService: UserService,
    private accountService: AccountService,
    private activatedRoute: ActivatedRoute,
    private router: Router,
    private eventManager: JhiEventManager,
    private modalService: NgbModal
  ) {}

  ngOnInit(): void {
    this.activatedRoute.data
      .pipe(
        flatMap(
          () => this.accountService.identity(),
          (data, account) => {
            this.page = data.pagingParams.page;
            this.previousPage = data.pagingParams.page;
            this.ascending = data.pagingParams.ascending;
            this.predicate = data.pagingParams.predicate;
            this.currentAccount = account;
            this.loadAll();
            this.userListSubscription = this.eventManager.subscribe('userListModification', () => this.loadAll());
          }
        )
      )
      .subscribe();
  }

  ngOnDestroy(): void {
    if (this.userListSubscription) {
      this.eventManager.destroy(this.userListSubscription);
    }
  }

...

}

如您所见，在UserManagementComponent类内部声明的“ page”和“ predicate”属性带有一个“！”。有人可以向我解释“！”的含义吗？并给我链接到文档？ 非常感谢！