I am curious if the type of listeners includes parameters for version compatibility reasons.

[MyohanMyolang]

When using useSyncExternal, they call subscribe like this:

  const handleStoreChange = () => {
    if (checkIfSnapshotChanged(inst)) {
      forceStoreRerender(fiber);
    }
  };
  return subscribe(handleStoreChange);

However, the current Listener type is defined as:

type Listner = (state: TState, prevState: TState) => void

Is this done for version compatibility reasons?

[dai-shi]

Are you referring to the difference between useSyncExternalStore listener and Zustand listener?

[MyohanMyolang]

umm maybe that's correct, they call what created in createStoreImpl subscribe then get handleStoreChange and add listners,
useSyncExternalStore gave no paramater function but listner type has 2 arguments state, and prevState
so i curious can it call listner, like this:

type Listner = () => void
const listners: Set<Listner> = new Set()

const setState: StoreApi<TState>['setState'] = (partial, replace) => {
  const nextState =
    typeof partial === 'function'
      ? (partial as (state: TState) => TState)(state)
      : partial
  if (!Object.is(nextState, state)) {
    state =
      replace ?? (typeof nextState !== 'object' || nextState === null)
        ? (nextState as TState)
        : Object.assign({}, state, nextState)
    listeners.forEach((listener) => listener())
  }
}

[dai-shi]

Sure, that's technically possible. It's the design choice that Zustand listener takes state and prevState.

[MyohanMyolang]

thank you for answer!