reflux

RefluxJS

A simple library for unidirectional dataflow architecture inspired by ReactJS Flux.

You can read an overview of Flux here, however the gist of it is to introduce a more functional programming style architecture by eschewing MVC like pattern and adopting a single data flow pattern.

╔═════════╗       ╔════════╗       ╔═════════════════╗
║ Actions ║──────>║ Stores ║──────>║ View Components ║
╚═════════╝       ╚════════╝       ╚═════════════════╝
     ^                                      │
     └──────────────────────────────────────┘

The pattern is composed of actions and data stores, where actions initiate new data to pass through data stores before coming back to the view components again. If a view component has an event that needs to make a change in the application's data stores, they need to do so by signalling to the stores through the actions available.

Comparing RefluxJS with Facebook Flux

The goal of the refluxjs project is to get this architecture easily up and running in your web application, both client-side or server-side. There are some differences between how this project works and how Facebook's proposed Flux architecture works:

You can read more in this blog post about React Flux vs Reflux.

Similarities with Flux

Some concepts are still in Reflux in comparison with Flux:

• There are actions
• There are data stores
• The data flow is unidirectional

Differences with Flux

Reflux has refactored Flux to be a bit more dynamic and be more FRP friendly:

• The singleton dispatcher is removed in favor for letting every action act as dispatcher instead.
• Because actions are listenable, the stores may listen to them. Stores don't need to have a big switch statements that does static type checking (of action types) with strings
• Stores may listen to other stores, i.e. it is possible to create stores that can aggregate data further, similar to a map/reduce.
• waitFor is replaced in favor to handle serial and parallel data flows:
• Aggregate data stores (mentioned above) may listen to other stores in serial
• Joins for joining listeners in parallel
• Action creators are not needed because RefluxJS actions are functions that will pass on the payload they receive to anyone listening to them

Examples

You can find some example projects at these locations:

• Todo Example Project - http://spoike.github.io/refluxjs-todo/

Installation

You can currently install the package as a npm package or bower.

NPM

The following command installs reflux as an npm package:

npm install reflux

Bower

The following command installs reflux as a bower component that can be used in the browser:

bower install reflux

Usage

For a full example check the test/index.js file.

Creating actions

Create an action by calling Reflux.createAction.

var statusUpdate = Reflux.createAction();

An action is a functor that can be invoked like any function.

statusUpdate(); // Invokes the action statusUpdate

It is as simple as that. There is also a convenience function for creating multiple actions.

var Actions = Reflux.createActions([
    "statusUpdate",
    "statusEdited",
    "statusAdded"
  ]);

// Actions object now contains the actions
// with the names given in the array above
// that may be invoked as usual

Actions.statusUpdate();

Action hooks

There are a couple of hooks avaiable for each action.

• preEmit - Is called before the action emits an event. It receives the arguments from the action invocation. If it returns something other than undefined, that will be used as arguments for shouldEmit and subsequent emission.

• shouldEmit - Is called after preEmit and before the action emits an event. By default it returns true which will let the action emit the event. You may override this if you need to check the arguments that the action receives and see if it needs to emit the event.

Example usage:

Actions.statusUpdate.preEmit = function() { console.log(arguments); };
Actions.statusUpdate.shouldEmit = function(value) {
    return value > 0;
};

Actions.statusUpdate(0);
Actions.statusUpdate(1);
// Should output: 1

You can also set the hooks by sending them in a definition object as you create the action:

var action = Reflux.createAction({
    preEmit: function(){...},
    shouldEmit: function(){...}
});

Creating data stores

Create a data store much like ReactJS's own React.createClass by passing a definition object to Reflux.createStore. You may set up all action listeners in the init function and register them by calling the store's own listenTo function.

// Creates a DataStore
var statusStore = Reflux.createStore({

    // Initial setup
    init: function() {

        // Register statusUpdate action
        this.listenTo(statusUpdate, this.output);
    },

    // Callback
    output: function(flag) {
        var status = flag ? 'ONLINE' : 'OFFLINE';

        // Pass on to listeners
        this.trigger(status);
    }

});

In the above example, whenever the action is called, the store's output callback will be called with whatever parameters was sent in the action. E.g. if the action is called as statusUpdate(true) then the flag argument in output function is true.

A data store is a publisher much like the actions, so they too have the preEmit and shouldEmit hooks.

Listening to many actions at once

Since it is a very common pattern to listen to all actions from a createActions call in a store init call, the store has a listenToMany function that takes an object of listenables. Instead of doing this:

var actions = Reflux.createActions(["fireBall","magicMissile"]);

var Store = Reflux.createStore({
    init: function() {
        this.listenTo(actions.fireBall,this.fireBall);
        this.listenTo(actions.magicMissile,this.magicMissile);
    },
    onFireBall: function(){
        // whoooosh!
    },
    onMagicMissile: function(){
        // bzzzzapp!
    }
});

...you can do this:

var actions = Reflux.createActions(["fireBall","magicMissile"]);

var Store = Reflux.createStore({
    init: function() {
        this.listenToAll(actions);
    },
    onFireBall: function(){
        // whoooosh!
    },
    onMagicMissile: function(){
        // bzzzzapp!
    }
});

This will add listeners to all actions actionName who have a corresponding onActionName (or actionName if you prefer) method in the store. Thus if the actions object should also have included an iceShard spell, that would simply be ignored.

The listenables shorthand

To make things more convenient still, if you give an object of actions to the listenables property of the store definition, that will be automatically passed to listenToMany. So the above example can be simplified even further:

var actions = Reflux.createActions(["fireBall","magicMissile"]);

var Store = Reflux.createStore({
    listenables: actions,
    onFireBall: function(){
        // whoooosh!
    },
    onMagicMissile: function(){
        // bzzzzapp!
    }
});

The listenables property can also be an array of such objects, in which case all of them will be sent to listenToMany. This allows you to do convenient things like this:

var Store = Reflux.createStore({
    listenables: [require('./darkspells'),require('./lightspells'),{healthChange:require('./healthstore')}],
    // rest redacted
});

Listening to changes in data store

In your component, register to listen to changes in your data store like this:

// Fairly simple view component that outputs to console
function ConsoleComponent() {

    // Registers a console logging callback to the statusStore updates
    statusStore.listen(function(status) {
        console.log('status: ', status);
    });
};

var consoleComponent = new ConsoleComponent();

Invoke actions as if they were functions:

statusUpdate(true);
statusUpdate(false);

With the setup above this will output the following in the console:

status:  ONLINE
status:  OFFLINE

React component example

Register your component to listen for changes in your data stores, preferably in the componentDidMount lifecycle method and unregister in the componentWillUnmount, like this:

var Status = React.createClass({
    initialize: function() { },
    onStatusChange: function(status) {
        this.setState({
            currentStatus: status
        });
    },
    componentDidMount: function() {
        this.unsubscribe = statusStore.listen(this.onStatusChange);
    },
    componentWillUnmount: function() {
        this.unsubscribe();
    },
    render: function() {
        // render specifics
    }
});

Convenience mixin for React

You always need to unsubscribe components from observed actions and stores upon unmounting. To simplify this process you can use mixins in React. There is a convenience mixin available at Reflux.ListenerMixin. Using that, the above example can be written like thus:

var Status = React.createClass({
    mixins: [Reflux.ListenerMixin],
    onStatusChange: function(status) {
        this.setState({
            currentStatus: status
        });
    },
    componentDidMount: function() {
        this.listenTo(statusStore, this.onStatusChange);
    },
    render: function() {
        // render specifics
    }
});

The mixin provides the listenTo method for the React component, that works much like the one found in the Reflux's stores, and handles the listeners during mount and unmount for you. You also get the same listenToMany method as the store has.

Using Reflux.listenTo

If you're not reliant on any special logic for the this.listenTo calls inside componentDidMount, you can instead use a call to Reflux.listenTo as a mixin. That will automatically set up the componentDidMount and the rest for you, as well as add the ListenerMixin functionality. With this our example above can be reduced even further:

var Status = React.createClass({
    mixins: [Reflux.listenTo(statusStore,"onStatusChange")],
    onStatusChange: function(status) {
        this.setState({
            currentStatus: status
        });
    },
    render: function() {
        // render using `this.state.currentStatus`
    }
});

You can have multiple calls to Reflux.listenTo in the same mixins array.

There is also Reflux.listenToMany which works in exactly the same way, exposing listener.listenToMany.

Using Reflux.connect

If all you want to do is update the state of your component to whatever the data store transmits, you can use Reflux.connect(listener,[stateKey]) as a mixin. If you supply a stateKey the state will be updated through this.setState({<stateKey>:data}), otherwise this.setState(data). Here's the example above changed to use this syntax:

var Status = React.createClass({
    mixins: [Reflux.connect(statusStore,"currentStatus")],
    render: function() {
        // render using `this.state.currentStatus`
    }
});

Listening to changes in other data stores (aggregate data stores)

A store may listen to another store's change, making it possible to safely chain stores for aggregated data without affecting other parts of the application. A store may listen to other stores using the same listenTo function as with actions:

// Creates a DataStore that listens to statusStore
var statusHistoryStore = Reflux.createStore({
    init: function() {

        // Register statusStore's changes
        this.listenTo(statusStore, this.output);

        this.history = [];
    },

    // Callback
    output: function(statusString) {
        this.history.push({
            date: new Date(),
            status: statusString
        });
        // Pass the data on to listeners
        this.trigger(this.history);
    }

});

Advanced usage

Switching EventEmitter

Don't like to use the EventEmitter provided? You can switch to another one, such as NodeJS's own like this:

// Do this before creating actions or stores

Reflux.setEventEmitter(require('events').EventEmitter);

Switching nextTick

Whenever action functors are called, they return immediately through the use of setTimeout (nextTick function) internally.

You may switch out for your favorite setTimeout, nextTick, setImmediate, et al implementation:

// node.js env
Reflux.nextTick(process.nextTick);

For better alternative to setTimeout, you may opt to use the setImmediate polyfill.

Joining parallel listeners with composed listenables

Reflux makes it easy to listen to actions and stores that emit events in parallel. You can use this feature to compose and share listenable objects (composed listenables) among several stores.

var theTide = Reflux.all(waveAction, timeStore);

var clockStore = Reflux.createStore({
    init: function() {
        this.listenTo(theTide, this.theTideCallback);
    },
    theTideCallback: function(waveActionArgs, timeStoreArgs) {
      // ...
    }
});

// node.js environment
if (process.env.DEVELOPMENT) {
    theTide.listenTo(console.log.bind(console), window);
}

Reflux.all always passes the last arguments that a listenable emitted to your callback, discarding subsequent emits. Arguments are passed in order. This means that the first argument which the callback receives, is the set of arguments which was emitted by the first listenable that was passed to Reflux.all and so on for the other arguments.

Comparison with Flux's waitFor()

The Reflux.all functionality is similar to Flux's waitFor(), but differs in a few aspects:

• Composed listenables may be reused by other stores
• Composed listenables always emit asynchronously
• Actions and stores may emit multiple times before the composed listenable (theTide in the example above) emits
• Action and store callbacks are not executed in a single synchronous iteration

Sending default data with the listenTo function

The listenTo function provided by the Store and the ListenerMixin has a third parameter that accepts a callback. This callback will be invoked when the listener is registered with whatever the getDefaultData is returning.

var exampleStore = Reflux.createStore({
    init: function() {},
    getDefaultData: function() {
        return "the initial data";
    }
});

// Anything that will listen to the example store
this.listenTo(exampleStore, onChangeCallback, initialCallback)

// initialCallback will be invoked immediately with "the initial data" as first argument

Remember the listenToMany method? In case you use that with other stores, it supports getDefaultData. That data is sent to the normal listening callback, or a this.on<Listenablename>Default method if that exists.

Colophon

List of contributors is available on Github.

This project is licensed under BSD 3-Clause License. Copyright (c) 2014, Mikael Brassman.

For more information about the license for this particular project read the LICENSE.md file.

This project uses eventemitter3, is currently MIT licensed and has it's license information here.

Changelog

v0.1.8

• Added Reflux.connect, Reflux.listenTo, listenToMany conveniences. See #63 and #75
• Stores may now use a listenables prop #63 to automatically register actions to callbacks
• preEmit may now map or transform the action payload by returning something. See 58 and #78
• Reflux now exposes a keep for easier introspection on actions and stores #56
• Added mixin interfaces ListenerMethods and PublisherMethods making it possible for users to extend Reflux's actions and stores. See #45