feat: add scroll_restoration component - #57
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Introduces a component that saves and restores scroll positions across client-side navigation. - JS side: ScrollRestoration component that intercepts pushState/ replaceState and popstate events to save scroll positions keyed by pathname. Restores scroll via requestAnimationFrame after each render. Disables browser's native scrollRestoration on mount. - Python side: scroll_restoration(*children) component that wraps children in a scroll-aware div and renders the hidden JS component. Exported from reactpy_router top-level. - Tests: basic rendering test and scroll preservation test that scrolls, navigates away, and verifies restoration on return. - Docs: added scroll_restoration to reference/components.md. - Changelog: updated Unreleased section.
- Use module-level _scrollPositions dict instead of useRef so saved scroll positions persist across route transitions (component remounts). - Restore scroll on mount (useEffect[] with cleanup) rather than on every render, preventing scroll jumps on re-renders. - Consume (delete) scroll position after restoration so it fires once per navigation cycle.
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July 21, 2026 15:10
Preact may perform multiple render commits during a single navigation event (server VDOM -> layout effects -> client-side effects). Each commit can reset scroll position. Fix by retrying scrollTo each animation frame (up to 5 retries) until the position sticks.
The ScrollRestoration component is reused by Preact across route navigations (same component type at the same VDOM position). The mount effect (with [] deps) only fires once, so the restoration logic must run in a post-render effect (no deps) to detect pathname changes. Key changes: - Post-render effect restores scroll on every render if a saved position exists for the current pathname - Position is kept alive (not deleted) so Preact render commits during navigation don't lose it - Retry across rAF frames (up to 10) to survive Preact's multi-commit navigation cycle - Python: use 'min-height: 100vh' instead of 'height: 100%' to not constrain document height
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Description
Adds a
scroll_restorationcomponent that saves and restores scroll positions across client-side navigation, analogous to React Router'sScrollRestorationcomponent.The component:
<div>pushState/replaceStateto save scroll before navigationpopstate(browser back/forward) as wellrequestAnimationFrameafter each renderscrollRestorationon mount to prevent interferenceCloses #31
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