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Created June 27, 2018 00:55
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Copy of Redux' createStore to ease migrations from Flux to Redux
// This file is base is based on, with some modifications
// for flux's actionTypes and other validations
import isPlainObject from 'lodash/isPlainObject';
import { createStore } from 'redux';
* This is a copy of Redux's createStore. Only the dispatch function is modified.
* It passes the action Type as parameter to the callbacks registered by store.subscribe *
* /
* These are private action types reserved by Redux.
* For any unknown actions, you must return the current state.
* If the current state is undefined, you must return the initial state.
* Do not reference these action types directly in your code.
export var ActionTypes = {
INIT: '@@redux/INIT'
* Creates a Redux store that holds the state tree.
* The only way to change the data in the store is to call `dispatch()` on it.
* There should only be a single store in your app. To specify how different
* parts of the state tree respond to actions, you may combine several reducers
* into a single reducer function by using `combineReducers`.
* @param {Function} reducer A function that returns the next state tree, given
* the current state tree and the action to handle.
* @param {any} [initialState] The initial state. You may optionally specify it
* to hydrate the state from the server in universal apps, or to restore a
* previously serialized user session.
* If you use `combineReducers` to produce the root reducer function, this must be
* an object with the same shape as `combineReducers` keys.
* @param {Function} enhancer The store enhancer. You may optionally specify it
* to enhance the store with third-party capabilities such as middleware,
* time travel, persistence, etc. The only store enhancer that ships with Redux
* is `applyMiddleware()`.
* @returns {Store} A Redux store that lets you read the state, dispatch actions
* and subscribe to changes.
export default function createFluxStore(reducer, initialState, enhancer) {
if (typeof initialState === 'function' && typeof enhancer === 'undefined') {
enhancer = initialState;
initialState = undefined;
if (typeof enhancer !== 'undefined') {
if (typeof enhancer !== 'function') {
throw new Error('Expected the enhancer to be a function.');
return enhancer(createStore)(reducer, initialState);
if (typeof reducer !== 'function') {
throw new Error('Expected the reducer to be a function.');
var currentReducer = reducer;
var currentState = initialState;
var currentListeners = [];
var nextListeners = currentListeners;
var isDispatching = false;
function ensureCanMutateNextListeners() {
if (nextListeners === currentListeners) {
nextListeners = currentListeners.slice();
* Reads the state tree managed by the store.
* @returns {any} The current state tree of your application.
function getState() {
return currentState;
* Adds a change listener. It will be called any time an action is dispatched,
* and some part of the state tree may potentially have changed. You may then
* call `getState()` to read the current state tree inside the callback.
* You may call `dispatch()` from a change listener, with the following
* caveats:
* 1. The subscriptions are snapshotted just before every `dispatch()` call.
* If you subscribe or unsubscribe while the listeners are being invoked, this
* will not have any effect on the `dispatch()` that is currently in progress.
* However, the next `dispatch()` call, whether nested or not, will use a more
* recent snapshot of the subscription list.
* 2. The listener should not expect to see all states changes, as the state
* might have been updated multiple times during a nested `dispatch()` before
* the listener is called. It is, however, guaranteed that all subscribers
* registered before the `dispatch()` started will be called with the latest
* state by the time it exits.
* @param {Function} listener A callback to be invoked on every dispatch.
* @returns {Function} A function to remove this change listener.
function subscribe(listener) {
if (typeof listener !== 'function') {
throw new Error('Expected listener to be a function.');
var isSubscribed = true;
return function unsubscribe() {
if (!isSubscribed) {
isSubscribed = false;
var index = nextListeners.indexOf(listener);
nextListeners.splice(index, 1);
* Dispatches an action. It is the only way to trigger a state change.
* The `reducer` function, used to create the store, will be called with the
* current state tree and the given `action`. Its return value will
* be considered the **next** state of the tree, and the change listeners
* will be notified.
* The base implementation only supports plain object actions. If you want to
* dispatch a Promise, an Observable, a thunk, or something else, you need to
* wrap your store creating function into the corresponding middleware. For
* example, see the documentation for the `redux-thunk` package. Even the
* middleware will eventually dispatch plain object actions using this method.
* @param {Object} action A plain object representing “what changed”. It is
* a good idea to keep actions serializable so you can record and replay user
* sessions, or use the time travelling `redux-devtools`. An action must have
* a `type` property which may not be `undefined`. It is a good idea to use
* string constants for action types.
* @returns {Object} For convenience, the same action object you dispatched.
* Note that, if you use a custom middleware, it may wrap `dispatch()` to
* return something else (for example, a Promise you can await).
function dispatch(action) {
if (!isPlainObject(action)) {
throw new Error(
'Actions must be plain objects. ' + 'Use custom middleware for async actions.'
if (typeof action.type === 'undefined') {
if (typeof action.actionType === 'undefined') {
throw new Error(
'Actions may not have an undefined "type" property. ' +
'Have you misspelled a constant?'
} else {
action.type = action.actionType;
if (isDispatching) {
throw new Error('Reducers may not dispatch actions.');
try {
isDispatching = true;
currentState = currentReducer(currentState, action);
} finally {
isDispatching = false;
var listeners = (currentListeners = nextListeners);
for (var i = 0; i < listeners.length; i++) {
return action;
* Replaces the reducer currently used by the store to calculate the state.
* You might need this if your app implements code splitting and you want to
* load some of the reducers dynamically. You might also need this if you
* implement a hot reloading mechanism for Redux.
* @param {Function} nextReducer The reducer for the store to use instead.
* @returns {void}
function replaceReducer(nextReducer) {
if (typeof nextReducer !== 'function') {
throw new Error('Expected the nextReducer to be a function.');
currentReducer = nextReducer;
dispatch({ type: ActionTypes.INIT });
// When a store is created, an "INIT" action is dispatched so that every
// reducer returns their initial state. This effectively populates
// the initial state tree.
dispatch({ type: ActionTypes.INIT });
return {
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