What is Flux in React ?

Flux is an architectural pattern and a set of principles for managing state in a React application. It was developed by Facebook to address the challenges of managing the flow of data in large and complex React applications. Flux is not a library or a framework but rather a design pattern that provides a unidirectional data flow and clear separation of concerns.

Key concepts in Flux:

1. Unidirectional Data Flow:
   Flux enforces a unidirectional flow of data, meaning that data flows in a single direction through the application. This makes it easier to understand how the state changes over time, as updates occur in a predictable manner.
2. Actions:
   Actions represent events or user interactions that trigger updates to the application state. They are simple objects with a type property and optional payload.
3. Dispatcher:
   The Dispatcher is responsible for distributing actions to the registered stores. It acts as a central hub that manages the flow of data. When an action is dispatched, the dispatcher ensures that the corresponding store is notified.
4. Stores:
   Stores contain the application state and logic for handling actions. They register with the dispatcher and update their state in response to dispatched actions. Each store represents a specific domain or part of the application state.
5. Views (React Components):
   React components (views) subscribe to stores and update their UI in response to changes in the state. Components are kept simple and focused on rendering based on the data they receive from stores.

Flux provides a clear separation of concerns and helps in avoiding cascading updates and unpredictable state changes. It’s important to note that Flux is more of an architectural pattern, and there are different implementations of Flux, including the original Facebook Flux, as well as popular libraries like Redux and MobX, which are inspired by Flux and provide additional features.

In summary, Flux is a design pattern that helps manage the flow of data in React applications by enforcing a unidirectional data flow and providing clear roles for actions, dispatcher, stores, and views. While the original Flux pattern has influenced the development of state management libraries, like Redux, the core principles of unidirectional data flow and separation of concerns continue to be relevant in modern React applications.

Let’s create a simple example of a Flux-like architecture in a React application. For simplicity, I’ll use basic JavaScript without any external libraries

// Action Types
const ActionTypes = {
  INCREMENT: 'INCREMENT',
  DECREMENT: 'DECREMENT',
};

// Action Creators
const incrementAction = () => ({
  type: ActionTypes.INCREMENT,
});

const decrementAction = () => ({
  type: ActionTypes.DECREMENT,
});

// Dispatcher
const Dispatcher = {
  callbacks: [],

  register(callback) {
    this.callbacks.push(callback);
  },

  dispatch(action) {
    this.callbacks.forEach(callback => callback(action));
  },
};

// Store
const CounterStore = {
  state: 0,

  getState() {
    return this.state;
  },

  handleAction(action) {
    switch (action.type) {
      case ActionTypes.INCREMENT:
        this.state += 1;
        break;
      case ActionTypes.DECREMENT:
        this.state -= 1;
        break;
      default:
        break;
    }

    // Notify subscribers (React components) about the state change
    this.notifyChange();
  },

  subscribe(callback) {
    Dispatcher.register(callback);
  },

  notifyChange() {
    Dispatcher.dispatch(this.state);
  },
};

// React Component
class CounterComponent extends React.Component {
  constructor() {
    super();
    this.state = {
      count: CounterStore.getState(),
    };

    // Subscribe to the store to receive updates
    CounterStore.subscribe(() => {
      this.setState({ count: CounterStore.getState() });
    });
  }

  handleIncrement = () => {
    // Dispatch an increment action
    CounterStore.handleAction(incrementAction());
  };

  handleDecrement = () => {
    // Dispatch a decrement action
    CounterStore.handleAction(decrementAction());
  };

  render() {
    return (
      <div>
        <p>Count: {this.state.count}</p>
        <button onClick={this.handleIncrement}>Increment</button>
        <button onClick={this.handleDecrement}>Decrement</button>
      </div>
    );
  }
}

// Render the React Component
ReactDOM.render(<CounterComponent />, document.getElementById('root'));

In this example:

• ActionTypes: Enumerates the types of actions that can be performed.
• Dispatcher: Manages the distribution of actions to registered stores.
• CounterStore: Represents the store containing the application state and logic to handle actions.
• CounterComponent: A React component that subscribes to the store and updates its UI in response to state changes.

When the “Increment” or “Decrement” buttons are clicked, actions are dispatched, and the store updates its state accordingly. The React component subscribes to the store and re-renders when the state changes, reflecting the updated count. This example provides a simplified illustration of the Flux architecture in a React application. In a real-world scenario, you might consider using libraries like Redux or MobX for a more robust and scalable implementation.

Flux is a design pattern developed at Facebook that was designed to keep data flowing in one direction.

What does React or Flux have to do with functional JavaScript ?

• Flux provides a way to provide the data that React will use to create the UI
• In Flux, application state data is managed outside of React components in stores. Stores hold and change the data, and are the only thing that can update a view in Flux

What is dispatcher in React ?

An action provides the instructions and data required to make a change. Actions are dispatched using a central control component called the dispatcher

About Flux Implementations

There are different approaches to the implementation of Flux. A few libraries have been open-sourced based upon specific implementations of this design pattern. Here are a few approaches to Flux worth mentioning

• Flux:Facebook’s Flux is the design pattern that we just covered. The Flux library includes an implementation of a dispatcher.
• Reflux:A simplified approach to unidirectional data flow that focuses on actions, stores, and views
• Flummox:A Flux implementation that allows you to build Flux modules through extending JavaScript classes
• Fluxible:A Flux framework created by Yahoo for working with isomorphic
• Redux:A Flux-like library that achieves modularity through functions instead of objects.
• MobX:A state management library that uses observables to respond to changes in state.