The issue you're experiencing—where the child page automatically scrolls to the same position as the parent page—is primarily caused by how browsers and React Router handle navigation and scroll positions. Here's a detailed explanation of the possible causes:
Browser's Default Scroll Behavior Browsers are designed to remember the scroll position of a page when you navigate away and return to it. This behavior is intended to improve user experience by maintaining context during navigation. When you navigate from one route to another (e.g., from a parent page to a child page), the browser might retain the scroll position of the parent page and apply it to the child page, especially if the child page has similar content or structure.
React Router's Scroll Handling React Router v5 and Below: React Router does not automatically reset the scroll position when navigating between routes. If the parent page was scrolled down, the child page might inherit that scroll position unless explicitly reset. React Router v6+: While React Router v6 introduced better support for scroll restoration, it still relies on the browser's default behavior unless you use the ScrollRestoration component or manually handle scrolling.
Scrollable Containers If your application uses a scrollable container (e.g., a with overflow-y: auto or overflow-y: scroll) instead of relying on the window's scroll, the scroll position of that container might persist between route changes. For example, if the parent page has a scrollable container scrolled to a specific position, the same container in the child page might start at that position unless explicitly reset.
CSS or Layout Issues If the child page has a similar layout or structure to the parent page, the browser might assume the scroll position should be the same. For example, if both pages have a long list or a large block of content, the browser might scroll the child page to match the parent page's scroll position.
useEffect or Scroll Reset Logic If you're using useEffect to reset the scroll position, ensure it runs at the correct time. For example: If the useEffect dependency array is missing or incorrect, the scroll reset might not trigger. If the useEffect runs after the page renders, there might be a slight delay, causing the scroll position to persist briefly.
Dynamic Content Loading If your child page loads content dynamically (e.g., via an API call), the scroll position might be applied before the content is fully loaded. This can cause the page to appear scrolled down even if you intended it to start at the top.
Hash Routing or Anchors If your application uses hash-based routing (e.g., #section) or anchor links, the browser might scroll to a specific section of the page automatically, overriding any scroll reset logic.
Summary of Causes
Browser's default scroll restoration behavior.
React Router not resetting scroll positions by default.
Scrollable containers retaining their scroll positions.
Similar layouts or structures between parent and child pages.
Improper timing or implementation of scroll reset logic.
Dynamic content loading causing scroll position shifts.
Hash routing or anchor links influencing scroll behavior.
How to Debug
Check if the issue occurs with window scrolling or a specific scrollable container.
Verify if the useEffect or scroll reset logic is running correctly.
Inspect the layout and structure of both the parent and child pages to identify similarities.
Test with static content to rule out dynamic loading issues