for循环第二次单击Dom元素在操纵up中不起作用

Question

我有主类别>子类别>使用puppeteer选择随机项目的项目，我正在使用for循环，但是for循环的第二次迭代不起作用...

出现类似enter image description here

的错误

export class SomeComponent implements OnInit {

  AlertsCollection: any = [];
  alertsDataSource = new MatTableDataSource(this.AlertsCollection);
  @ViewChild('AlertsMatSort') alertSort: MatSort;
  @ViewChild("AlertsPaginator") paginator: MatPaginator;

  constructor(private alertsService: AlertsService, private alertsHubService: AlertsHubService,
    private changeDetectorRefs: ChangeDetectorRef, private modalService: NgbModal) {}


  ngOnInit() {
    this.alertsHubService.subscribe(utils.url_root);
    this.alertNotificationProxy = this.alertsHubService.generateProxy();
    this.alertsService.registerProxy(this.alertNotificationProxy, 'updateDashboard', (message: any[]) => {
      this.populateAlertTableSource(message)
    });
  }

  ngAfterViewInit() {
    this.alertsDataSource.paginator = this.paginator;
    this.alertsDataSource.sort = this.alertSort;
  }

  populateAlertTableSource(message: any) {
    this.AlertsCollection = message
    this.alertsDataSource.data = this.AlertsCollection;
    this.alertsDataSource.paginator = this.paginator;
    this.alertsDataSource.sort = this.alertSort;
    this.alertsTable.renderRows();
    this.refresh();
  }


  deleteAlert(alert: any) {
    this.alertsService.skipAlert(alert).subscribe(() => {
        var index = this.AlertsCollection.indexOf(alert, 0);
        if (index > -1)
          this.AlertsCollection.splice(index, 1);
        this.alertsDataSource.data = this.AlertsCollection;
        this.alertsTable.renderRows();
      },
      (error: AppError) => {
        console.log(error);
        throw error;
      }
    );
  }


  refresh() {
    this.changeDetectorRefs.detectChanges();
  }

}

Answer 1

 (Math.floor(Math.random() * 0) + 1) === 1 //true

也许var this.menuCategoryLength为0，并且您的代码尝试获取someSelector:nth-child(1)