localStorage

import { createLocalStorageAdapter, createNusmStore } from "nusm"

const preferences = createNusmStore(
  { density: "comfortable", theme: "system" },
  {
    adapter: createLocalStorageAdapter(),
    persist: { strategy: "entire" },
    storeId: "preferences",
  },
)

Options

interface StorageAdapterOptions {
  storage?: StorageLike
  prefix?: string
  serialize?: (value: unknown) => string
  deserialize?: (raw: string) => unknown
  pacer?: false | {
    wait?: number
    maxWait?: number
    leading?: boolean
    trailing?: boolean
  }
}

Custom namespace and serializer

const adapter = createLocalStorageAdapter({
  prefix: "acme-state",
  serialize: JSON.stringify,
  deserialize: JSON.parse,
  pacer: { trailing: true, wait: 150 },
})

The current scheduler uses wait, leading, and trailing; maxWait remains in the public type but is not forwarded yet.

Always change serializer and deserializer together. Existing values written in another format need an explicit migration or a compatible decoder.

Cross-tab updates

The adapter listens for browser storage events and emits set or remove events for matching prefixed keys. nusm then reloads the configured persistence unit and updates live state without writing the same external value back.

The browser does not send a storage event back to the tab that performed the write; nusm already has that tab's current in-memory state.

Constraints

• Browser storage is synchronous; keep values reasonably small.
• Quota and privacy-mode failures reach onError.
• Any script on the same origin can read local storage. Do not put secrets there.
• Construct the default adapter only where window.localStorage exists.