Redux is a popular state management library for JavaScript applications. It provides a way to centralize the state of an application in a single store, making it easier to debug, test, and reason about the state changes in the application.
One of the significant benefits of Redux is its support for time travel, which allows developers to inspect the state of their application at any point in time, including past and future states. This makes it easier to debug and understand the state changes in the application.
In this article, we’ll go over the fundamental ideas of Redux, such as store creation, action creation, action dispatching, reducer functions, combining reducers, and connecting to React components.
1. Store Creation: To build a Redux store, developers use the redux library’s createStore function and send in a root reducer as an argument. A root reducer is a collection of reducers that describe how the state in an application changes. Here’s an illustration of a store built in Redux:
Javascript
import { createStore } from 'redux'; import rootReducer from './reducers'; // Create the redux store by calling createStore // and passing in the root reducer const store = createStore(rootReducer); |
2. Action Creation: Redux actions are simple objects that explain changes to the state. Developers define an object with a type property and any other data required to describe the change to make an action. Here’s an illustration of how to make an action in Redux:
Javascript
// Define a action creator function that // takes test as an argument and returns // an action object. const addTodo = (text) => { return { // Describes the action to be taken type: 'ADD_TODO', text }; }; |
3. Dispatching Actions: To dispatch an action and update the state, developers call the dispatch method on the store and pass in the action as an argument. Here is an example of dispatching an action in Redux:
Javascript
// Dispatch the addTodo action by calling // store.dispatch and passing in the action store.dispatch(addTodo('Learn Redux')); |
4. Reducer Functions: Reducers are pure functions in Redux that accept the current state and an action and return the next state. Here’s an example of a Redux reducer function:
Javascript
// Define a reducer function that accepts the // current state and an action and return the // next state const todoReducer = (state = [], action) => { // To handle different action types switch (action.type) { // For the ADD_TODO action type case 'ADD_TODO': return [ // Create a new array with the // existing todos ...state, { // Add a new todo with the text // from the action text: action.text, // Set the completed property // to false completed: false } ]; default: // For any other action types return state; } }; |
5. Combining Reducers: If an application has multiple reducers, developers can use the redux library’s combineReducers function to combine them into a single root reducer. Here’s an example of how to combine reducers in Redux:
Javascript
// Combine multiple reducers into a single // root reducer using combineReducers import { combineReducers } from 'redux'; const rootReducer = combineReducers({ todos: todoReducer, visibilityFilter: visibilityFilterReducer }); |
6. Connecting to React Component: Developers use the react-redux library’s connect function to connect a Redux store to React components. Here’s an example of a Redux store being linked to a React component:
Javascript
// Connect a Redux store to a react component // using the connect import { connect } from 'react-redux'; // Define functional components that accepts // todos as a prop const TodoList = ({ todos }) => ( <ul> /* map over the todos array to render each todo */ {todos.map((todo, index) => ( <li key={index}>{todo.text}</li> ))} </ul> ); const mapStateToProps = (state) => { return { // Specify which properties should // be mapped to props todos: state.todos }; }; export default connect(mapStateToProps)(TodoList); |
Output
Conclusion: Redux is a strong state management library for JavaScript applications. It streamlines the management of state and makes it simpler to test, debug, and analyze state changes in an application. Developers can effectively manage the state of their applications using Redux by following the steps for store creation, action creation, dispatching actions, reducer functions, combining reducers, and connecting to React components.
