🚧 AsyncStorage

AsyncStorage is an unencrypted, asynchronous, persistent, key-value storage system that is global to the app. It should be used instead of LocalStorage.

It is recommended that you use an abstraction on top of AsyncStorage instead of AsyncStorage directly for anything more than light usage since it operates globally. Vega provides AsyncStorageWithKeyScope or you can create your own abstraction.

On Vega, AsyncStorage is backed by a SQLite database. On iOS, AsyncStorage is backed by native code that stores small values in a serialized dictionary and larger values in separate files. On Android, AsyncStorage will use either RocksDB or SQLite based on what is available.

The AsyncStorage JavaScript code is a facade that provides a clear JavaScript API, real Error objects, and non-multi functions. Each method in the API returns a Promise object.

Importing the AsyncStorage library:

import {AsyncStorage} from '@amazon-devices/react-native-kepler';

Persisting data:

_storeData = async () => {
  try {
    await AsyncStorage.setItem(
      '@MySuperStore:key',
      'I like to save it.',
    );
  } catch (error) {
    // Error saving data
  }
};

Fetching data:

_retrieveData = async () => {
  try {
    const value = await AsyncStorage.getItem('TASKS');
    if (value !== null) {
      // We have data!!
      console.log(value);
    }
  } catch (error) {
    // Error retrieving data
  }
};

Reference

Methods

getItem()

static getItem(key: string, [callback]: ?(error: ?Error, result: ?string) => void)

Fetches an item for a key and invokes a callback upon completion. Returns a Promise object.

Parameters:

setItem()

static setItem(key: string, value: string, [callback]: ?(error: ?Error) => void)

Sets the value for a key and invokes a callback upon completion. Returns a Promise object.

Note: Ensure your keys are determinate or you may not be able to get or remove them later. Keys with timestamps or other variable information may be difficult to identify later and could result in wasted storage.

Parameters:

removeItem()

static removeItem(key: string, [callback]: ?(error: ?Error) => void)

Removes an item for a key and invokes a callback upon completion. Returns a Promise object.

Parameters:

mergeItem() Vega Not Available

static mergeItem(key: string, value: string, [callback]: ?(error: ?Error) => void)

Merges an existing key value with an input value, assuming both values are stringified JSON. Returns a Promise object.

NOTE: This is not supported by all native implementations.

Parameters:

Example:

let UID123_object = {
  name: 'Chris',
  age: 30,
  traits: {hair: 'brown', eyes: 'brown'},
};
// You only need to define what will be added or updated
let UID123_delta = {
  age: 31,
  traits: {eyes: 'blue', shoe_size: 10},
};

AsyncStorage.setItem(
  'UID123',
  JSON.stringify(UID123_object),
  () => {
    AsyncStorage.mergeItem(
      'UID123',
      JSON.stringify(UID123_delta),
      () => {
        AsyncStorage.getItem('UID123', (err, result) => {
          console.log(result);
        });
      },
    );
  },
);

// Console log result:
// => {'name':'Chris','age':31,'traits':
//    {'shoe_size':10,'hair':'brown','eyes':'blue'}}

clear()

static clear([callback]: ?(error: ?Error) => void)

Erases all AsyncStorage for all clients, libraries, etc. You probably don't want to call this; use removeItem or multiRemove to clear only your app's keys. Returns a Promise object.

Parameters:

getAllKeys() Vega Not Available

static getAllKeys([callback]: ?(error: ?Error, keys: ?Array<string>) => void)

Gets all keys known to your app; for all callers, libraries, etc. Returns a Promise object.

Parameters:

flushGetRequests() Vega Not Available

static flushGetRequests(): [object Object]

Flushes any pending requests using a single batch call to get the data.

multiGet()

static multiGet(keys: Array<string>, [callback]: ?(errors: ?Array<Error>, result: ?Array<Array<string>>) => void)

This allows you to batch the fetching of items given an array of key inputs. Your callback will be invoked with an array of corresponding key-value pairs found:

multiGet(['k1', 'k2'], cb) -> cb([['k1', 'val1'], ['k2', 'val2']])

The method returns a Promise object.

Parameters:

Example:

AsyncStorage.getAllKeys((err, keys) => {
  AsyncStorage.multiGet(keys, (err, stores) => {
    stores.map((result, i, store) => {
      // get at each store's key/value so you can work with it
      let key = store[i][0];
      let value = store[i][1];
    });
  });
});

multiSet()

static multiSet(keyValuePairs: Array<Array<string>>, [callback]: ?(errors: ?Array<Error>) => void)

Use this as a batch operation for storing multiple key-value pairs. When the operation completes you'll get a single callback with any errors.

Note: Ensure your keys are determinate or you may not be able to get or remove them later. Keys with timestamps or other variable information may be difficult to identify later and could result in wasted storage.

multiSet([['k1', 'val1'], ['k2', 'val2']], cb);

The method returns a Promise object.

Parameters:

multiRemove()

static multiRemove(keys: Array<string>, [callback]: ?(errors: ?Array<Error>) => void)

Call this to batch the deletion of all keys in the keys array. Returns a Promise object.

Parameters:

Example:

let keys = ['k1', 'k2'];
AsyncStorage.multiRemove(keys, err => {
  // keys k1 & k2 removed, if they existed
  // do most stuff after removal (if you want)
});

removeValuesForKeysWithPrefix() Vega v2

static removeValuesForKeysWithPrefix(prefix: string, [callback]: ?(errors: ?Array<Error>) => void)

Call this to items with keys that start with a specified prefix. Returns a Promise object.

Parameters:

Example:

let keys = ['k1', 'k2'];
AsyncStorage.removeValuesForKeysWithPrefix("MyAppNetworking_", err => {
  // keys that begin with `MyAppNetworking_` will be removed
  // do stuff after removal (if you want)
});

multiMerge() Vega Not Available

static multiMerge(keyValuePairs: Array<Array<string>>, [callback]: ?(errors: ?Array<Error>) => void)

Batch operation to merge in existing and new values for a given set of keys. This assumes that the values are stringified JSON. Returns a Promise object.

NOTE: This is not supported by all native implementations.

Parameters:

Example:

// first user, initial values
let UID234_object = {
  name: 'Chris',
  age: 30,
  traits: {hair: 'brown', eyes: 'brown'},
};

// first user, delta values
let UID234_delta = {
  age: 31,
  traits: {eyes: 'blue', shoe_size: 10},
};

// second user, initial values
let UID345_object = {
  name: 'Marge',
  age: 25,
  traits: {hair: 'blonde', eyes: 'blue'},
};

// second user, delta values
let UID345_delta = {
  age: 26,
  traits: {eyes: 'green', shoe_size: 6},
};

let multi_set_pairs = [
  ['UID234', JSON.stringify(UID234_object)],
  ['UID345', JSON.stringify(UID345_object)],
];
let multi_merge_pairs = [
  ['UID234', JSON.stringify(UID234_delta)],
  ['UID345', JSON.stringify(UID345_delta)],
];

AsyncStorage.multiSet(multi_set_pairs, err => {
  AsyncStorage.multiMerge(multi_merge_pairs, err => {
    AsyncStorage.multiGet(['UID234', 'UID345'], (err, stores) => {
      stores.map((result, i, store) => {
        let key = store[i][0];
        let val = store[i][1];
        console.log(key, val);
      });
    });
  });
});

// Console log results:
// => UID234 {"name":"Chris","age":31,"traits":{"shoe_size":10,"hair":"brown","eyes":"blue"}}
// => UID345 {"name":"Marge","age":26,"traits":{"shoe_size":6,"hair":"blonde","eyes":"green"}}

Last updated: May 13, 2026