anna-shakhova · Aug 20, 2026 · Aug 19, 2026 · Aug 20, 2026
@@ -118,7 +118,7 @@ export class DataController extends DataHelperMixin(modules.Controller) {
 
   public dataSourceChanged!: Callback<[]>;
 
-  public rowIndicesCorrected!: Callback<[RowIndexCorrection]>;
+  public rowIndicesChanged!: Callback<[RowIndexCorrection]>;
 
   protected _lastRenderingPageIndex?: number;
 
@@ -187,7 +187,7 @@ export class DataController extends DataHelperMixin(modules.Controller) {
   }
 
   protected callbackNames(): string[] {
-    return ['changed', 'loadingChanged', 'dataErrorOccurred', 'pageChanged', 'dataSourceChanged', 'pushed', 'rowIndicesCorrected'];
+    return ['changed', 'loadingChanged', 'dataErrorOccurred', 'pageChanged', 'dataSourceChanged', 'pushed', 'rowIndicesChanged'];
   }
 
   protected callbackFlags(name?: string): CallbackFlags | undefined {
@@ -1148,7 +1148,7 @@ export class DataController extends DataHelperMixin(modules.Controller) {
       change.isLiveUpdate = true;
     }
 
-    this.rowIndicesCorrected.fire(
+    this.rowIndicesChanged.fire(
       (rowIndex: number): number => this.getRowIndexCorrection(rowIndex, oldItems, newIndexByKey),
     );
   }

@@ -31,6 +31,7 @@ import type { RowIndexCorrection } from '@ts/grids/grid_core/data_controller/typ
 import type { EditingController } from '@ts/grids/grid_core/editing/m_editing';
 import type { RowsView } from '@ts/grids/grid_core/views/m_rows_view';
 import type { RowsViewScrollEvent } from '@ts/grids/grid_core/views/types';
+import type { VirtualScrollingDataControllerExtension } from '@ts/grids/grid_core/virtual_scrolling/m_virtual_scrolling';
 import { memoize } from '@ts/utils/memoize';
 
 import {
@@ -128,7 +129,7 @@ export class KeyboardNavigationController extends KeyboardNavigationControllerCo
 
   private _testInteractiveElement: any;
 
-  protected _dataController!: Controllers['data'];
+  protected _dataController!: DataController & Partial<VirtualScrollingDataControllerExtension>;
 
   private _selectionController!: Controllers['selection'];
 
@@ -184,8 +185,8 @@ export class KeyboardNavigationController extends KeyboardNavigationControllerCo
     this.initDocumentHandlers();
 
     // init runs again on option changes, so drop the previous subscription first
-    this._dataController.rowIndicesCorrected.remove(this.handleRowIndicesCorrected);
-    this._dataController.rowIndicesCorrected.add(this.handleRowIndicesCorrected);
+    this._dataController.rowIndicesChanged.remove(this.rowIndicesChangedHandler);
+    this._dataController.rowIndicesChanged.add(this.rowIndicesChangedHandler);
   }
 
   public dispose(): void {
@@ -198,10 +199,10 @@ export class KeyboardNavigationController extends KeyboardNavigationControllerCo
     );
     clearTimeout(this._updateFocusTimeout);
     accessibility.unsubscribeVisibilityChange();
-    this._dataController.rowIndicesCorrected.remove(this.handleRowIndicesCorrected);
+    this._dataController.rowIndicesChanged.remove(this.rowIndicesChangedHandler);
   }
 
-  private readonly handleRowIndicesCorrected = (
+  private readonly rowIndicesChangedHandler = (
     getRowIndexCorrection: RowIndexCorrection,
   ): void => {
     const focusedCellPosition = this._focusedCellPosition;
@@ -2062,15 +2063,24 @@ export class KeyboardNavigationController extends KeyboardNavigationControllerCo
     return this._isCellValid($cell);
   }
 
-  private _isLastRow(rowIndex: number): boolean {
-    const dataController = this._dataController;
+  private getMaxRowIndex(): number {
+    const lastLoadedRowIndex = this._dataController.items().length - 1;
+    const virtualItemsCount = this._dataController.virtualItemsCount?.();
+
+    if (!virtualItemsCount) {
+      return lastLoadedRowIndex;
+    }
 
+    return lastLoadedRowIndex + this._dataController.getRowIndexOffset() + virtualItemsCount.end;
+  }
+
+  private _isLastRow(rowIndex: number): boolean {
     if (this._isVirtualRowRender()) {
-      return rowIndex >= (dataController as any).getMaxRowIndex();
+      return rowIndex >= this.getMaxRowIndex();
     }
 
     const lastVisibleIndex = Math.max(
-      ...dataController.items()
+      ...this._dataController.items()
         .map((item, index) => (item.visible !== false ? index : -1)),
     );
 
@@ -3194,21 +3204,6 @@ const editing = (Base: ModuleType<EditingController>) => class EditingController
   }
 };
 
-const data = (Base: ModuleType<DataController>) => class DataControllerKeyboardExtender extends Base {
-  private getMaxRowIndex() {
-    let result = this.items().length - 1;
-    // @ts-expect-error
-    const virtualItemsCount = this.virtualItemsCount();
-
-    if (virtualItemsCount) {
-      const rowIndexOffset = this.getRowIndexOffset();
-      result += rowIndexOffset + virtualItemsCount.end;
-    }
-
-    return result;
-  }
-};
-
 const adaptiveColumns = (Base: ModuleType<AdaptiveColumnsController>) => class AdaptiveColumnsKeyboardExtender extends Base {
   protected _showHiddenCellsInView({ viewName, $cells, isCommandColumn }) {
     super._showHiddenCellsInView.apply(this, arguments as any);
@@ -3259,7 +3254,6 @@ export const keyboardNavigationModule: import('../m_types').Module = {
     },
     controllers: {
       editing,
-      data,
       adaptiveColumns,
       keyboardNavigation: keyboardNavigationScrollableA11yExtender,
     },

@@ -1,6 +1,8 @@
 import { Deferred, when } from '@js/core/utils/deferred';
 import { isObject, isString } from '@js/core/utils/type';
 
+import type { VirtualItemsCount } from './types';
+
 const LEGACY_SCROLLING_MODE = 'scrolling.legacyMode';
 
 const needTwoPagesLoading = (that) => that.option('scrolling.loadTwoPagesOnStart') || that._controller.isVirtual() || that._controller.getViewportItemIndex() > 0;
@@ -405,7 +407,7 @@ export class VirtualDataLoader {
     return count;
   }
 
-  private virtualItemsCount() {
+  public virtualItemsCount(): VirtualItemsCount {
     let pageIndex = getBeginPageIndex(this);
     if (pageIndex < 0) {
       pageIndex = this._dataOptions.pageIndex();

@@ -0,0 +1,5 @@
+/** How many virtual (not loaded) items sit before and after the loaded window. */
+export interface VirtualItemsCount {
+  begin: number;
+  end: number;
+}
@@ -21,6 +21,7 @@ import type { ErrorHandlingViewController } from '@ts/grids/grid_core/error_hand
 import type { ModuleType } from '@ts/grids/grid_core/m_types';
 import type { ResizingController } from '@ts/grids/grid_core/views/m_grid_view';
 import type { RowsView } from '@ts/grids/grid_core/views/m_rows_view';
+import type { VirtualItemsCount } from '@ts/grids/grid_core/virtual_data_loader/types';
 
 import type { ChangedEvent } from '../data_source_adapter/types';
 import gridCoreUtils from '../m_utils';
@@ -456,7 +457,16 @@ export const dataSourceAdapterExtender = (Base: ModuleType<DataSourceAdapter>) =
     return proxyDataSourceAdapterMethod(this, 'loadIfNeed', [...arguments]);
   }
 };
-export const data = (Base: ModuleType<DataController>) => class VirtualScrollingDataControllerExtender extends Base {
+
+export interface VirtualScrollingDataControllerExtension {
+  virtualItemsCount: () => VirtualItemsCount | undefined;
+}
+
+export const virtualScrollingDataControllerExtender = (
+  Base: ModuleType<DataController>,
+): ModuleType<
+  DataController & VirtualScrollingDataControllerExtension
+> => class VirtualScrollingDataControllerExtender extends Base {
   private _loadViewportParams: any;
 
   private _allItems: any;
@@ -1278,16 +1288,14 @@ export const data = (Base: ModuleType<DataController>) => class VirtualScrolling
     return viewportParams && viewportParams.skip + viewportParams.take;
   }
 
-  private virtualItemsCount() {
+  public virtualItemsCount(): VirtualItemsCount | undefined {
     const rowsScrollController = this._rowsScrollController;
 
     if (rowsScrollController) {
-      // @ts-expect-error
-      return rowsScrollController.virtualItemsCount.apply(rowsScrollController, arguments);
+      return rowsScrollController.virtualItemsCount();
     }
 
-    const dataSource = this._dataSource;
-    return dataSource?.virtualItemsCount.apply(dataSource, arguments);
+    return this._dataSource?.virtualItemsCount() as VirtualItemsCount | undefined;
   }
 
   public pageIndex(): number;
@@ -1960,7 +1968,7 @@ export const virtualScrollingModule = {
   },
   extenders: {
     controllers: {
-      data,
+      data: virtualScrollingDataControllerExtender,
       resizing,
     },
     views: {

@@ -7,6 +7,7 @@ import { Deferred } from '@js/core/utils/deferred';
 import { each } from '@js/core/utils/iterator';
 import { isDefined } from '@js/core/utils/type';
 import { getWindow } from '@js/core/utils/window';
+import type { VirtualItemsCount } from '@ts/grids/grid_core/virtual_data_loader/types';
 
 import gridCoreUtils from '../m_utils';
 import { VirtualDataLoader } from '../virtual_data_loader/m_virtual_data_loader';
@@ -167,7 +168,7 @@ class VirtualScrollController {
     return this._isVirtual;
   }
 
-  private virtualItemsCount() {
+  public virtualItemsCount(): VirtualItemsCount | undefined {
     if (isVirtualMode(this)) {
       const dataOptions = this._dataOptions;
       const totalItemsCount = dataOptions.totalItemsCount();
@@ -186,8 +187,7 @@ class VirtualScrollController {
         };
       }
 
-      // @ts-expect-error
-      return this._dataLoader.virtualItemsCount.apply(this._dataLoader, arguments);
+      return this._dataLoader.virtualItemsCount();
     }
 
     return undefined;

@@ -6,9 +6,9 @@ import type { ModuleType } from '@ts/grids/grid_core/m_types';
 import gridCoreUtils from '@ts/grids/grid_core/m_utils';
 import type { RowsView } from '@ts/grids/grid_core/views/m_rows_view';
 import {
-  data as virtualScrollingDataControllerExtender,
   dataSourceAdapterExtender as virtualScrollingDataSourceAdapterExtender,
   rowsView as virtualScrollingRowsViewExtender,
+  virtualScrollingDataControllerExtender,
   virtualScrollingModule,
 } from '@ts/grids/grid_core/virtual_scrolling/m_virtual_scrolling';
 

diff --git a/packages/devextreme/testing/helpers/gridBaseMocks.js b/packages/devextreme/testing/helpers/gridBaseMocks.js
@@ -255,11 +255,8 @@ module.exports = function($, gridCore, columnResizingReordering, domUtils, commo
             pageChanged: $.Callbacks(),
             dataSourceChanged: $.Callbacks(),
             pushed: $.Callbacks(),
-            rowIndicesCorrected: $.Callbacks(),
+            rowIndicesChanged: $.Callbacks(),
             fireError: function() { },
-            getMaxRowIndex: function() {
-                this.items().length - 1;
-            },
             loadViewport: commonUtils.noop,
             updateViewport: commonUtils.noop,
             getScrollingTimeout: function() {