DataGrid: Fix extra request for the first page on load when starting on another page (T1326786)

[Alyar666]

No description provided.

[Copilot]

Pull request overview

Fixes an unnecessary extra data load triggered during DataGrid initialization when virtual scrolling starts on a non-first page (especially noticeable with asynchronously-rendered templates), ensuring only the intended page request is issued.

Changes:

• Added a guard in virtual scrolling viewport update logic to prevent loadViewport from firing while the initial scroll-to-page positioning is still pending.
• Simplified/clarified viewport “needs more items” calculation by normalizing take values.
• Added a TestCafe e2e regression test that validates only one remote load request occurs on init for a non-first page scenario (T1326786).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/devextreme/js/__internal/grids/grid_core/virtual_scrolling/m_virtual_scrolling.ts	Prevents updateViewport() from triggering an extra load until the viewport is positioned to the configured initial page.
e2e/testcafe-devextreme/tests/dataGrid/common/scrolling.ts	Adds an e2e regression test asserting a single { skip, take } request when initializing on a non-first page with async templates.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.

Comments suppressed due to low confidence (1)

e2e/testcafe-devextreme/tests/dataGrid/common/scrolling.ts:2179

• The test asserts the collected load options immediately after isReady(), but the extra request this regression targets can be triggered asynchronously (e.g., after delayed template rendering). As written, the test can pass even if a second request happens shortly after the assertion. Add a short wait and re-check the collected options to ensure no delayed extra request occurs.

  await t.expect(dataGrid.isReady()).ok();
  await t.expect(dataGrid.getScrollTop()).gt(0);
  await t.expect(dataGrid.apiPageIndex()).eql(10);

  const loadOptions = await getTestLoadOptions();

  await t.expect(loadOptions).eql([{ skip: 1000, take: 100 }]);