Enhanced navigation should not scroll before content renders #64054
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Pull Request Overview
This PR fixes a visual timing bug in enhanced navigation where scroll resets occurred before new content rendered, causing a noticeable flash. The solution introduces a new ScrollResetSchedule enum to coordinate scroll timing with DOM updates.
Key changes:
- Enhanced navigation now defers scroll resets until after new DOM content is applied
- Added
ScrollResetScheduleenum to track different timing phases for scroll resets - Implemented scroll position tracking in E2E tests to verify the fix
Reviewed Changes
Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| FormWithParentBindingContextTest.cs | Uses shared IsStale() extension method instead of local implementation |
| EnhancedNavigationTest.cs | Adds scroll timing regression tests with new observation utilities |
| WebDriverExtensions.cs | Introduces IsStale() extension and scroll observation infrastructure |
| ScrollOverrideScope.cs | New test utility that intercepts and logs window.scrollTo calls |
| NavigationManager.ts | Updates to use new scheduleScrollReset API with AfterBatch timing |
| NavigationEnhancement.ts | Schedules scroll resets for AfterDocumentUpdate instead of immediate execution |
| Renderer.ts | Implements ScrollResetSchedule enum and timing-based scroll reset logic |
| Boot.Web.ts | Triggers AfterDocumentUpdate scroll resets in the shared documentUpdated callback |
oroztocil
approved these changes
Oct 24, 2025
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Prevent visual flash during navigation
This is a timing bug, specially visible on browsers with slower connection or when the page intentionally delays rendering. Because enhanced page load fetches and applies the new DOM asynchronously, the immediate scroll-up run against the previous page's DOM. User sees a page A jump to the top and only after the fetch of new page is completed - the page B replaces it.
Description
ScrollResetSchedule.AfterDocumentUpdate, removing the flash that occurred while the old DOM was still visible.Boot.WebinvokesresetScrollIfNeeded(ScrollResetSchedule.AfterDocumentUpdate)from the shareddocumentUpdatedcallback so every enhanced navigation (including streaming SSR) scrolls exactly once, right after new content arrives.ScrollResetScheduleenum and only callswindow.scrollTowhen the requested phase triggers, instead of scrolling immediately.NavigationManagerrequestsAfterBatchwhen client-side navigation changes pages, letting the render batch complete before the scroll reset.WebDriverExtensions.IsStalehelpers and the scroll observation utilities so we rely on a single stale-element check and avoid copy/pasted extension method logic.Fixes #64015