items: any[] | ItemsSource;

itemTemplate: string | Template;

optional itemTemplates?: string | KeyedTemplate[];

off(
   event: "itemLoading", 
   callback: (args: EventData) => void, 
   thisArg?: any): void;

on(
   event: "itemLoading", 
   callback: (args: ItemEventData) => void, 
   thisArg?: any): void;

refresh(): void;