fluctuations

Yet another flux implementation

Formerly known as flux-redux.

Goals

• Simple Implementation
• Small API
• Flexible
• Functional rather than OO
• Reducer-style stores
• Actions as simple data
• Action interceptors for async stuff
• No singletons
• Easy to use with Immutable.js
• Easy to run isomorphically
• Easy to use with hot reloading

Install

npm install fluctuations

Usage

var fluctuations = require('fluctuations');
 
var store = fluctuations.createStore(
    function() {
        return { initial: 'data', number: 0 };
    },
    {
        CHANGE_MESSAGE: function(state, payload) {
            state.initial = payload.value;
            return state;
        },
        INC_NUMBER: function(state) {
            state.number += 1;
            return state;
        }
    }
);
 
var interceptor = fluctuations.createInterceptor({
    FETCH_MESSAGE: function(emit, payload) {
        emit("FETCH_MESSAGE_BEGIN");
        setTimeout(function() {
            emit("CHANGE_MESSAGE", { value: "whatever" });
        }, 2000);
    }
});
 
var flux = fluctuations.createDispatcher();
flux.addInterceptor('stuff', interceptor);
flux.addStore('stuff', store);
 
flux.listen("logging", function() {
    console.log(flux.get());
});
 
flux.dispatch("INC_NUMBER");

Concepts

Fluctuations is based around the Flux architecture as laid out by facebook. See the flux documentation for more information. We keep the concepts defined by facebook, but make a few tweaks. Most notably Action Creators are removed, and Action Interceptors are introduced to perform a similar role.

Action Interceptors

In early explanations of flux, the role of actions was a bit blurred. They seem to behave like commands and like events. As implementations were further clarified, Action Creators were explained as representing the command portion, while the data representation they sent to the dispatcher is referred to as the action. For many simple actions, this results in boilerplate code which translates a function call into a data payload. More complicated actions can use this layer of indirection to perform multiple actions, do asynchronous lookups etc.

The goal of action interceptors is to retain this capability, but remove the boilerplate code required in the common case. The dispatcher remains the central point for all communication. Stores and interceptors are attached to a dispatcher instance. Subscriptions are managed via the dispatcher, and the UI is expected to be able to call dispatch() directly.

Unlike creators, Interceptors sit behind the dispatcher. The actions which are dispatched into the dispatcher are intended to be treated like commands. If no interceptor exists then the action is treated like an event, and forwarded to all stores. If an interceptor chooses to handle the command, it is then freeto translate it into whatever event-like actions it wants to. Interceptors are also able to re-dispatch new commands and read the state of stores. This allows them full flexibility when deciding what events they must produce.

To summarise the key points here:

• Stores receive actions which should be treated like events
• The Dispatcher receives actions which should be treated like commands
• Action Interceptors capture a command and produce events
• If no interceptor exists, a command becomes an event

Hot Reloading

The practice of hot reloading is making a system which can receive new code at runtime, and incorporate it into itself - ideally behaving the same as if it had been started afresh. The goal being to reduce the feedback cycle between changes.

The simplest way to make code hot reloadable is to make it pure (stateless), as soon as state is introduced, we have to decide what to do with it when reloading.

To make hot reloading easier, fluctuations minimises the number of places state is held - everything is kept in the dispatcher. In addition, every time something is attached to the dispatcher it is required to pass a key which names it uniquely. This is used to ensure the same item is never duplicated.

Docs

None yet, for now you'll have to rely on examples:

• Counter - Basic data handling
• React Hot - React w/ hot module reloading and async data fetching
• React Isomorphic - React w/ hot module reloading, routing, route-aware async data fetching & server rendering

TODO

• High level tests
• Low level tests
• Cycle detection?
• Benchmarking / profiling
• Granular subscriptions
• Docs docs docs docs docs