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@react.dev in the old docs for useMemo (legacy.reactjs.org/docs/hooks-r...), you could read: > In the future, React may choose to “forget” some previously memoized values and recalculate them on next render But I can’t find any similar mentions of this in the new ones in react.dev/reference/re...

legacy.reactjs.orgHooks API Reference – ReactA JavaScript library for building user interfaces

Ayc0

@ayc0.dev

The new docs, even say: “React will return the same value again if the dependencies have not changed since the last render” Does it mean that going forward, React will 100% treat dependencies as exact and only re-compute useMemo when they changed, but not otherwise?

27/6/26, 6:20 pm0 reposts0 likes

Ayc0

@ayc0.dev

27 June

@tkdodo.eu, do you know if React changed how it was handling `useMemo()` under the hood? (as you talked about it a few years ago in tkdodo.eu/blog/use-sta...)

tkdodo.euuseState for one-time initializationsWhy you shouldn't rely on useMemo for guaranteed referential stability but prefer useState instead

Dominik 🔮

@tkdodo.eu

27 June

It’s still the same: no semantic guarantee, only a performance improvement, your code should work exactly the same when useMemo is removed. If anything, offscreen rendering (<Activity>) will lead to more memos being thrown away.

Ayc0

@ayc0.dev

27 June

Interesting Do you know why Activity could lead to more recomputed memos?

Dominik 🔮

@tkdodo.eu

28 June

The old docs you mentioned used to say: "e.g. to free memory for offscreen components". I think this is still accurate