Use faster implementation for merging

lib/Onyx.js

@@ -6,8 +6,7 @@ import Storage from './storage';
 import * as Logger from './Logger';
 import cache from './OnyxCache';
 import createDeferredTask from './createDeferredTask';
-// eslint-disable-next-line rulesdir/prefer-import-module-contents
-import {fastMerge} from './fastMerge';
+import fastMerge from './fastMerge';
 
 // Keeps track of the last connectionID that was used so we can keep incrementing it
 let lastConnectionID = 0;
@@ -763,7 +762,7 @@ function applyMerge(key, data) {
  // Object values are merged one after the other
  return _.reduce(mergeValues, (modifiedData, mergeValue) => {
  // eslint-disable-next-line prefer-object-spread, rulesdir/prefer-underscore-method
- const newData = Object.assign({}, fastMerge(modifiedData, mergeValue));
+ const newData = Object.assign({}, fastMerge(modifiedData, mergeValue)); // lodash adds a small overhead so we don't use it here
 
  // We will also delete any object keys that are undefined or null.
  // Deleting keys is not supported by AsyncStorage so we do it this way.

lib/OnyxCache.js

@@ -1,6 +1,5 @@
 import _ from 'underscore';
-// eslint-disable-next-line rulesdir/prefer-import-module-contents
-import {fastMerge} from './fastMerge';
+import fastMerge from './fastMerge';
 
 const isDefined = _.negate(_.isUndefined);
 
@@ -112,7 +111,7 @@ class OnyxCache {
  */
  merge(data) {
  // eslint-disable-next-line prefer-object-spread, rulesdir/prefer-underscore-method
- this.storageMap = Object.assign({}, fastMerge(this.storageMap, data));
+ this.storageMap = Object.assign({}, fastMerge(this.storageMap, data)); // lodash adds a small overhead so we don't use it here
 
  const storageKeys = this.getAllKeys();
  const mergedKeys = _.keys(data);

lib/fastMerge.js

@@ -1,45 +1,69 @@
 // Mostly copied from https://medium.com/@lubaka.a/how-to-remove-lodash-performance-improvement-b306669ad0e1
 
+let mergeObject;
+
+/**
+* Is the object Mergeable
+*
+* @param {*} val
+* @returns {*|boolean}
+*/
 function isMergeableObject(val) {
  const nonNullObject = val && typeof val === 'object';
  return nonNullObject
  && Object.prototype.toString.call(val) !== '[object RegExp]'
  && Object.prototype.toString.call(val) !== '[object Date]';
 }
 
-function mergeObject(target, source) {
+/**
+ * Merge Object and Arrays
+ *
+ * @param {{}|[]} target
+ * @param {{}|[]} source
+ * @returns {{}|[]}
+ */
+function fastMerge(target, source) {
+ // eslint-disable-next-line rulesdir/prefer-underscore-method
+ const array = Array.isArray(source); // lodash adds a small overhead so we don't use it here
+ if (array) {
+ return source;
+ }
+ return mergeObject(target, source);
+}
+
+/**
+* Merge Object
+*
+* @param {{}} target
+* @param {{}} source
+* @returns {{}}
+*/
+mergeObject = function (target, source) {
  const destination = {};
  if (isMergeableObject(target)) {
  // eslint-disable-next-line rulesdir/prefer-underscore-method
- const targetKeys = Object.keys(target);
+ const targetKeys = Object.keys(target); // lodash adds a small overhead so we don't use it here
  for (let i = 0; i < targetKeys.length; ++i) {
  const key = targetKeys[i];
  destination[key] = target[key];
  }
  }
  // eslint-disable-next-line rulesdir/prefer-underscore-method
- const sourceKeys = Object.keys(source);
+ const sourceKeys = Object.keys(source); // lodash adds a small overhead so we don't use it here
  for (let i = 0; i < sourceKeys.length; ++i) {
  const key = sourceKeys[i];
  if (source[key] === undefined) {
- // noop
- } else if (!isMergeableObject(source[key]) || !target[key]) {
+ // eslint-disable-next-line no-continue
+ continue;
+ }
+ if (!isMergeableObject(source[key]) || !target[key]) {
  destination[key] = source[key];
  } else {
- // eslint-disable-next-line no-use-before-define
  destination[key] = fastMerge(target[key], source[key]);
  }
  }
 
  return destination;
-}
+};
 
-// eslint-disable-next-line import/prefer-default-export, rulesdir/no-inline-named-export
-export function fastMerge(target, source) {
- // eslint-disable-next-line rulesdir/prefer-underscore-method
- const array = Array.isArray(source);
- if (array) {
- return source;
- }
- return mergeObject(target, source);
-}
+export default fastMerge;

lib/storage/providers/LocalForage.js

@@ -7,8 +7,7 @@
 import localforage from 'localforage';
 import _ from 'underscore';
 import SyncQueue from '../../SyncQueue';
-// eslint-disable-next-line rulesdir/prefer-import-module-contents
-import {fastMerge} from '../../fastMerge';
+import fastMerge from '../../fastMerge';
 
 localforage.config({
  name: 'OnyxDB',
@@ -26,7 +25,7 @@ const provider = {
  .then((existingValue) => {
  const newValue = _.isObject(existingValue)
  // eslint-disable-next-line prefer-object-spread, rulesdir/prefer-underscore-method
- ? Object.assign({}, fastMerge(existingValue, value))
+ ? Object.assign({}, fastMerge(existingValue, value)) // lodash adds a small overhead so we don't use it here
  : value;
  return localforage.setItem(key, newValue);
  });