State, Actions, Reducers and Store in Redux

Redux is a predictable state container for JavaScript applications. It helps manage the state of your application in a predictable way and makes it easier to understand and debug your application's state changes. Redux follows a unidirectional data flow, and its core concepts include State, Actions, Reducers, and the Store.

1. State:

   • The state represents the current state of your application. It is a plain JavaScript object that holds the data you want to manage. In Redux, the state is typically stored as a single immutable object.

2. Actions:

   • Actions are plain JavaScript objects that describe events in your application. They are the only way to send data to the Redux store. An action must have a type property that describes the type of action being performed, and it may also include additional data (payload).

   // Example action
   const increment = {
     type: 'INCREMENT',
     payload: 1,
   };
   

3. Reducers:

   • Reducers are pure functions that take the current state and an action as arguments and return a new state. Reducers specify how the application's state changes in response to actions. They should not modify the existing state but rather return a new state based on the provided state and action.

   // Example reducer
   const counterReducer = (state = 0, action) => {
     switch (action.type) {
       case 'INCREMENT':
         return state + action.payload;
       case 'DECREMENT':
         return state - action.payload;
       default:
         return state;
     }
   };
   

4. Store:

   • The store is the core of Redux and holds the application state. It is created by passing a reducer function to the createStore function from the Redux library. The store has methods to dispatch actions, subscribe to state changes, and get the current state.

   import { createStore } from 'redux';
   
   const store = createStore(counterReducer);
   

   With these concepts, the flow in a Redux application typically looks like this:

   1. Something happens in the application (e.g., a user clicks a button).
   2. An action is dispatched to the Redux store.
   3. The reducer processes the action and returns a new state.
   4. The store updates its state.
   5. Components that are subscribed to the store re-render based on the updated state.

This unidirectional flow makes it easier to track and understand how the state changes in your application.