@statesync/persistence

---

@statesync/persistence / createLocalStorageBackend

Function: createLocalStorageBackend()

function createLocalStorageBackend<T>(options): StorageBackend<T>;

Defined in: persistence/src/storage/local-storage.ts:89

Creates a StorageBackend that persists snapshot data using the browser's localStorage API.

Data stored in localStorage persists across browser sessions and tab closures, making it suitable for long-lived application state. The storage is synchronous under the hood but exposed through an async interface for API consistency.

Browser compatibility: Supported in all modern browsers. Requires a secure context (HTTPS) in some browsers for full functionality. Not available in Web Workers or Service Workers.

Storage limits: localStorage has a ~5MB per-origin limit in most browsers. For larger data, consider using createIndexedDBBackend instead.

Type Parameters

Type Parameter	Description
T	The type of the state data stored within snapshot envelopes.

Parameters

Parameter	Type	Description
options	LocalStorageBackendOptions	Configuration options for the localStorage backend.

Returns

StorageBackend<T>

A StorageBackend instance backed by localStorage.

Throws

Throws a descriptive error wrapping QuotaExceededError when the localStorage quota is exceeded during a save operation.

Throws

Throws a descriptive error when stored data cannot be deserialized during a load operation (e.g., corrupted or incompatible data).

Examples

const storage = createLocalStorageBackend<MyState>({ key: 'my-app-state' });

// Save a snapshot
await storage.save({ revision: '1', data: { count: 42 } });

// Load the snapshot
const snapshot = await storage.load();
console.log(snapshot?.data.count); // 42

// Clear stored data
await storage.clear();

const storage = createLocalStorageBackend<MyState>({
  key: 'my-app-state',
  serialize: (snapshot) => btoa(JSON.stringify(snapshot)),
  deserialize: (data) => JSON.parse(atob(data)),
});