Backends and serializers

Use localStorage, sessionStorage, memory, or a custom serializer through the core entry point.

Storage backends

Pass any Storage-compatible backend. Use sessionStorage for tab-scoped data, or createMemoryStorage() for tests and server-side rendering.

import { createStorage, createMemoryStorage } from 'ultrastorage';

const storage = createStorage({
  storage: typeof window === 'undefined' ? createMemoryStorage() : undefined,
});

Memory storage

Returns an in-memory Storage implementation. Useful for tests or server-side usage.

const memory = createMemoryStorage();
const storage = createStorage({ storage: memory });

Use a separate memory backend for each server request when storing request-specific data. Separate instances must share the same backend object to receive each other’s local notifications.

Custom serialization

Don’t like devalue? Bring your own stringify/parse and we won’t judge. Much.

import superjson from 'superjson';

const storage = createStorage({
  serializer: { stringify: superjson.stringify, parse: superjson.parse },
});

If you provide your own serializer and want to keep devalue out of your bundle entirely, import from ultrastorage/core instead. The only difference is that serializer is required.

import { createStorage } from 'ultrastorage/core';
import superjson from 'superjson';

const storage = createStorage({
  serializer: { stringify: superjson.stringify, parse: superjson.parse },
});

Changing serializers can make existing entries unreadable. Prefer a new prefix when changing formats; see the migration caveats.