WhenVisible useEffect function is not recreated when params change. #2152

[Loeffeldude]

Closes #2152. Adds the needed dependencies to the useEffect and adds a few refs to keep the same fetching behavior as before.

[PedroAugustoRamalhoDuarte]

Thanks for the PR @Loeffeldude !!

[joetannenbaum]

Thanks for the PR @Loeffeldude. I'm a little confused as to why the fetching flag was split into two separate flags and converted to refs. If I revert it back to a simple useState it seems to work as expected, want to make sure I'm not missing something.

[Loeffeldude]

We split into two refs (fetchedOnceRef and fetchingRef) because we're handling two distinct problems:

Has this content ever been fetched? (for the always prop logic)
Is there currently a fetch in progress? (to prevent concurrent fetches)

Using a single useState for fetching would create problems because:

State updates are asynchronous and will trigger rerenders
The IntersectionObserver callback can fire multiple times while a fetch is in progress
When props like buffer change, the effect recreates the observer callback, which could capture stale state values

Using refs:

• Avoids unnecessary rerenders
• Provides synchronous access in the observer callback
• Prevents race conditions
• Correctly handles the always prop logic
• Maintains correct behavior when the effect needs to recreate the observer

The ref-based approach is more robust for handling edge cases and async behavior.