chore: Adds typescript support

Closes #27.

Author: itsjgf

package.json

@@ -2,6 +2,7 @@
   "name": "@react-native-community/async-storage",
   "version": "1.1.0",
   "description": "Asynchronous, persistent, key-value storage system for React Native.",
+  "types": "./types/index.d.ts",
   "main": "lib/index.js",
   "author": "Krzysztof Borowy <krizzu.dev@gmail.com>",
   "contributors": [],

types/index.d.ts

@@ -0,0 +1,88 @@
+// CREDITS: This types are based on the original work made by all the people who contributed to @types/react-native
+
+declare module '@react-native-community/async-storage' {
+  /**
+   * AsyncStorage is a simple, 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.
+   *
+   * 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](http://rocksdb.org/) or SQLite
+   * based on what is available.
+   *
+   * @see https://github.com/react-native-community/react-native-async-storage/blob/master/docs/API.md
+   */
+  export interface AsyncStorageStatic {
+    /**
+     * Fetches key and passes the result to callback, along with an Error if there is any.
+     */
+    getItem(key: string, callback?: (error?: Error, result?: string) => void): Promise<string | null>;
+
+    /**
+     * Sets value for key and calls callback on completion, along with an Error if there is any
+     */
+    setItem(key: string, value: string, callback?: (error?: Error) => void): Promise<void>;
+
+    removeItem(key: string, callback?: (error?: Error) => void): Promise<void>;
+
+    /**
+     * Merges existing value with input value, assuming they are stringified json. Returns a Promise object.
+     * Not supported by all native implementation
+     */
+    mergeItem(key: string, value: string, callback?: (error?: Error) => void): Promise<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 own keys instead.
+     */
+    clear(callback?: (error?: Error) => void): Promise<void>;
+
+    /**
+     * Gets all keys known to the app, for all callers, libraries, etc
+     */
+    getAllKeys(callback?: (error?: Error, keys?: string[]) => void): Promise<string[]>;
+
+    /**
+     * multiGet invokes callback with an array of key-value pair arrays that matches the input format of multiSet
+     */
+    multiGet(
+      keys: string[],
+      callback?: (errors?: Error[], result?: [string, string][]) => void
+    ): Promise<[string, string][]>;
+
+    /**
+     * multiSet and multiMerge take arrays of key-value array pairs that match the output of multiGet,
+     *
+     * multiSet([['k1', 'val1'], ['k2', 'val2']], cb);
+     */
+    multiSet(keyValuePairs: string[][], callback?: (errors?: Error[]) => void): Promise<void>;
+
+    /**
+     * Delete all the keys in the keys array.
+     */
+    multiRemove(keys: string[], callback?: (errors?: Error[]) => void): Promise<void>;
+
+    /**
+     * Merges existing values with input values, assuming they are stringified json.
+     * Returns a Promise object.
+     *
+     * Not supported by all native implementations.
+     */
+    multiMerge(keyValuePairs: string[][], callback?: (errors?: Error[]) => void): Promise<void>;
+  }
+
+  export function useAsyncStorage(key: string): {
+    getItem(callback?: (error?: Error, result?: string) => void): Promise<string | null>;
+    setItem(value: string, callback?: (error?: Error) => void): Promise<void>;
+    mergeItem(value: string, callback?: (error?: Error) => void): Promise<void>;
+    removeItem(callback?: (error?: Error) => void): Promise<void>;
+  }
+
+  const AsyncStorage: AsyncStorageStatic;
+
+  export default AsyncStorage;
+}