Function persistImpl

src/middleware/persist.ts:187–375

(config, baseOptions)

  }

const persistImpl: PersistImpl = (config, baseOptions) => (set, get, api) => {
  type S = ReturnType<typeof config>
  let options = {
    storage: createJSONStorage<S, void>(() => window.localStorage),
    partialize: (state: S) => state,
    version: 0,
    merge: (persistedState: unknown, currentState: S) => ({
      ...currentState,
      ...(persistedState as object),
    }),
    ...baseOptions,
  }

  let hasHydrated = false
  // Counter to track hydration versions and prevent race conditions
  // when multiple rehydrate() calls happen concurrently
  let hydrationVersion = 0
  const hydrationListeners = new Set<PersistListener<S>>()
  const finishHydrationListeners = new Set<PersistListener<S>>()
  let storage = options.storage

  if (!storage) {
    return config(
      (...args) => {
        console.warn(
          `[zustand persist middleware] Unable to update item '${options.name}', the given storage is currently unavailable.`,
        )
        set(...(args as Parameters<typeof set>))
      },
      get,
      api,
    )
  }

  const setItem = () => {
    const state = options.partialize({ ...get() })
    return (storage as PersistStorage<S, unknown>).setItem(options.name, {
      state,
      version: options.version,
    })
  }

  const savedSetState = api.setState

  api.setState = (state, replace) => {
    savedSetState(state, replace as any)
    return setItem()
  }

  const configResult = config(
    (...args) => {
      set(...(args as Parameters<typeof set>))
      return setItem()
    },
    get,
    api,
  )