React 19 issue with useWindowVirtualizer

[fat]

Describe the bug

Sorry for the drive by issue… 

We ran into a problem with react 19 today that was a pita to track down. So dropping it here incase it's useful to anyone.

We had a simple useWindowVirutalizer in a client component in next.js w/ react 19 (like this):

const virtualizer = useWindowVirtualizer({
  count: branches.length,
  estimateSize: () => 66,
  overscan: 5,
  scrollMargin: listRef.current?.offsetTop ?? 0,
});

and virtualizerRef.getVirtualItems() was being hoisted / memo'd by the compiler in such a way that it was always returning 0 for getVirutalItems.

To fix it we just dropped the virtualizer in a ref…

	const virtualizer = useWindowVirtualizer({
		count: branches.length,
		estimateSize: () => 66,
		overscan: 5,
		scrollMargin: listRef.current?.offsetTop ?? 0,
	});

	// we do this because react 19 was optimzing it away
	const virtualizerRef = useRef(virtualizer);
	
	…
	
	virtualizerRef.current.getVirtualItems() // etc…

Your minimal, reproducible example

n/a

Steps to reproduce

Don't have time to spin up a test case sorry!

Expected behavior

Expected getVirtualItems() to return items.

How often does this bug happen?

Every time

Screenshots or Videos

No response

Platform

macos, chrome, react 19

tanstack-virtual version

3.7.0

TypeScript version

No response

Additional context

No response

Terms & Code of Conduct

• I agree to follow this project's Code of Conduct
• I understand that if my bug cannot be reliable reproduced in a debuggable environment, it will probably not be fixed and this issue may even be closed.

[Prains]

same issue here, but droppind a virtualizer in a ref does not helps

[izakfilmalter]

Running into the same issue. useRef seems to work for now for us.

[eqqe]

It gives me an issue with eslint however.

Ref values (the `current` property) may not be accessed during render. (https://react.dev/reference/react/useRef)eslint(react-compiler/react-compiler)

Edit: it might be removed in a PR
https://github.com/facebook/react/pull/30843/files

[cacabo]

+1, I am seeing this with:

{
    "@tanstack/react-virtual": "^3.11.1",
    "react": "^18.3.1",
    "react-compiler-runtime": "^19.0.0-beta-63b359f-20241101",
    "react-dom": "^18.3.1",
}

Putting a hook in the component after .getVirtualItems appears to be another workaround

Another option is "use no memo"

https://react.dev/learn/react-compiler#something-is-not-working-after-compilation

[piecyk]

Yep, 'use no memo' seems like a reasonable temporary workaround! 👍