nav2/lib/store.ts

export const createStore = <StateType>(initialState: StateType) => {
  let state: StateType = initialState
  const listeners = new Set<() => void>()

  return {
    getState: () => state,
    subscribe: (listener) => {
      listeners.add(listener)
      return () => {listeners.delete(listener)}
    },
    setState: (newState) => {
      state = newState
      listeners.forEach((listener) => listener())
    },
  }
}