stack/packages/mosaic/framework/skills/vueuse-functions/references/useStorageAsync.md

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useStorageAsync

Reactive Storage in with async support.

Usage

The basic usage please refer to useStorage.

Wait First Loaded

When user entering your app, useStorageAsync() will start loading value from an async storage, sometimes you may get the default initial value, not the real value stored in storage at the very beginning.

import { useStorageAsync } from '@vueuse/core';

const accessToken = useStorageAsync('access.token', '', SomeAsyncStorage);

// accessToken.value may be empty before the async storage is ready
console.log(accessToken.value); // ""

setTimeout(() => {
  // After some time, the async storage is ready
  console.log(accessToken.value); // "the real value stored in storage"
}, 500);

In this case, you can wait the storage prepared, the returned value is also a Promise, so you can wait it resolved in your template or script.

// Use top-level await if your environment supports it
const accessToken = await useStorageAsync('access.token', '', SomeAsyncStorage);

console.log(accessToken.value); // "the real value stored in storage"

If you must wait multiple storages, put them into a Promise.allSettled()

router.onReady(async () => {
  await Promise.allSettled([accessToken, refreshToken, userData]);

  app.mount('app');
});

There is a callback named onReady in options:

import { useStorageAsync } from '@vueuse/core';

// Use ES2024 Promise.withResolvers, you may use any Deferred object or EventBus to do same thing.
const { promise, resolve } = Promise.withResolvers();

const accessToken = useStorageAsync('access.token', '', SomeAsyncStorage, {
  onReady(value) {
    resolve(value);
  },
});

// At main.ts
router.onReady(async () => {
  // Let's wait accessToken loaded
  await promise;

  // Now accessToken has loaded, we can safely mount our app

  app.mount('app');
});

Simply use resolve as callback:

const accessToken = useStorageAsync('access.token', '', SomeAsyncStorage, {
  onReady: resolve,
});

Type Declarations

export interface UseStorageAsyncOptions<T> extends Omit<UseStorageOptions<T>, 'serializer'> {
  /**
   * Custom data serialization
   */
  serializer?: SerializerAsync<T>;
  /**
   * On first value loaded hook.
   */
  onReady?: (value: T) => void;
}
export declare function useStorageAsync(
  key: string,
  initialValue: MaybeRefOrGetter<string>,
  storage?: StorageLikeAsync,
  options?: UseStorageAsyncOptions<string>,
): RemovableRef<string> & Promise<RemovableRef<string>>;
export declare function useStorageAsync(
  key: string,
  initialValue: MaybeRefOrGetter<boolean>,
  storage?: StorageLikeAsync,
  options?: UseStorageAsyncOptions<boolean>,
): RemovableRef<boolean> & Promise<RemovableRef<boolean>>;
export declare function useStorageAsync(
  key: string,
  initialValue: MaybeRefOrGetter<number>,
  storage?: StorageLikeAsync,
  options?: UseStorageAsyncOptions<number>,
): RemovableRef<number> & Promise<RemovableRef<number>>;
export declare function useStorageAsync<T>(
  key: string,
  initialValue: MaybeRefOrGetter<T>,
  storage?: StorageLikeAsync,
  options?: UseStorageAsyncOptions<T>,
): RemovableRef<T> & Promise<RemovableRef<T>>;
export declare function useStorageAsync<T = unknown>(
  key: string,
  initialValue: MaybeRefOrGetter<null>,
  storage?: StorageLikeAsync,
  options?: UseStorageAsyncOptions<T>,
): RemovableRef<T> & Promise<RemovableRef<T>>;