Add web support to legacy AsyncStorage

Author: EvanBacon

Diff for: lib/AsyncStorage.web.js

@@ -0,0 +1,158 @@
+/**
+ * Copyright (c) Nicolas Gallagher.
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import merge from 'deep-assign';
+
+const mergeLocalStorageItem = (key, value) => {
+  const oldValue = window.localStorage.getItem(key);
+  const oldObject = JSON.parse(oldValue);
+  const newObject = JSON.parse(value);
+  const nextValue = JSON.stringify(merge({}, oldObject, newObject));
+  window.localStorage.setItem(key, nextValue);
+};
+
+const createPromise = (getValue, callback): Promise<*> => {
+  return new Promise((resolve, reject) => {
+    try {
+      const value = getValue();
+      if (callback) {
+        callback(null, value);
+      }
+      resolve(value);
+    } catch (err) {
+      if (callback) {
+        callback(err);
+      }
+      reject(err);
+    }
+  });
+};
+
+const createPromiseAll = (promises, callback, processResult): Promise<*> => {
+  return Promise.all(promises).then(
+    result => {
+      const value = processResult ? processResult(result) : null;
+      callback && callback(null, value);
+      return Promise.resolve(value);
+    },
+    errors => {
+      callback && callback(errors);
+      return Promise.reject(errors);
+    }
+  );
+};
+
+export default class AsyncStorage {
+
+  /**
+   * Fetches `key` value.
+   */
+  static getItem(key: string, callback?: Function): Promise<*> {
+    return createPromise(() => {
+      return window.localStorage.getItem(key);
+    }, callback);
+  }
+
+  /**
+   * Sets `value` for `key`.
+   */
+  static setItem(key: string, value: string, callback?: Function): Promise<*> {
+    return createPromise(() => {
+      window.localStorage.setItem(key, value);
+    }, callback);
+  }
+
+  /**
+   * Removes a `key`
+   */
+  static removeItem(key: string, callback?: Function): Promise<*> {
+    return createPromise(() => {
+      return window.localStorage.removeItem(key);
+    }, callback);
+  }
+
+  /**
+   * Merges existing value with input value, assuming they are stringified JSON.
+   */
+  static mergeItem(key: string, value: string, callback?: Function): Promise<*> {
+    return createPromise(() => {
+      mergeLocalStorageItem(key, value);
+    }, callback);
+  }
+
+  /**
+   * Erases *all* AsyncStorage for the domain.
+   */
+  static clear(callback?: Function): Promise<*> {
+    return createPromise(() => {
+      window.localStorage.clear();
+    }, callback);
+  }
+
+  /**
+   * Gets *all* keys known to the app, for all callers, libraries, etc.
+   */
+  static getAllKeys(callback?: Function): Promise<*> {
+    return createPromise(() => {
+      const numberOfKeys = window.localStorage.length;
+      const keys = [];
+      for (let i = 0; i < numberOfKeys; i += 1) {
+        const key = window.localStorage.key(i);
+        keys.push(key);
+      }
+      return keys;
+    }, callback);
+  }
+
+  /**
+   * (stub) Flushes any pending requests using a single batch call to get the data.
+   */
+  static flushGetRequests() {}
+
+  /**
+   * multiGet resolves to an array of key-value pair arrays that matches the
+   * input format of multiSet.
+   *
+   *   multiGet(['k1', 'k2']) -> [['k1', 'val1'], ['k2', 'val2']]
+   */
+  static multiGet(keys: Array<string>, callback?: Function): Promise<*> {
+    const promises = keys.map(key => AsyncStorage.getItem(key));
+    const processResult = result => result.map((value, i) => [keys[i], value]);
+    return createPromiseAll(promises, callback, processResult);
+  }
+
+  /**
+   * Takes an array of key-value array pairs.
+   *   multiSet([['k1', 'val1'], ['k2', 'val2']])
+   */
+  static multiSet(keyValuePairs: Array<Array<string>>, callback?: Function): Promise<*> {
+    const promises = keyValuePairs.map(item => AsyncStorage.setItem(item[0], item[1]));
+    return createPromiseAll(promises, callback);
+  }
+
+  /**
+   * Delete all the keys in the `keys` array.
+   */
+  static multiRemove(keys: Array<string>, callback?: Function): Promise<*> {
+    const promises = keys.map(key => AsyncStorage.removeItem(key));
+    return createPromiseAll(promises, callback);
+  }
+
+  /**
+   * Takes an array of key-value array pairs and merges them with existing
+   * values, assuming they are stringified JSON.
+   *
+   *   multiMerge([['k1', 'val1'], ['k2', 'val2']])
+   */
+  static multiMerge(keyValuePairs: Array<Array<string>>, callback?: Function): Promise<*> {
+    const promises = keyValuePairs.map(item => AsyncStorage.mergeItem(item[0], item[1]));
+    return createPromiseAll(promises, callback);
+  }
+}