search
HomeWeb Front-endJS TutorialAbout connecting react-redux in React and Redux (detailed tutorial)

This article mainly introduces react-redux, the connection between React and Redux. The editor thinks it is quite good, so I will share it with you now and give it as a reference. Let’s follow the editor to take a look

I have been exploring React-related things before, and I have a SPA project in hand, so I am ready to try Redux. Redux itself has no connection with React. It is a general Javscript App module used for App State management. To use Redux in a React project, a better way is to use the react-redux library to connect. What this means is that without react-redux, these two libraries will not be used together. react-redux provides some encapsulation, a more scientific way of organizing code, allowing us to use Redux in React code more comfortably.

I only learned about react-redux through the Redux documentation before. After a period of practice, I am going to look through the source code and make some relevant summaries. The npm version of the code I'm looking at is v4.0.0, which means the React version used is 0.14.x.

react-redux provides two key modules: Provider and connect.

Provider

Provider module is used as the container of the entire App. It is wrapped with another layer based on your original App Container. Its work is very simple. , which means accepting the Redux store as props and declaring it as one of the attributes of context. Subcomponents can conveniently access the store through this.context.store after declaring contextTypes. However, our components usually do not need to do this. The store is placed in the context for the following connect.

This is an example of using Provider:

// config app root
const history = createHistory()
const root = (
 <Provider store={store} key="provider">
  <Router history={history} routes={routes} />
 </Provider>
)

// render
ReactDOM.render(
 root,
 document.getElementById(&#39;root&#39;)
)

connect

This module is a real connection between Redux and React, just like its name Also called connect.

First consider how Redux works: First, a state is maintained in the store, we dispatch an action, and then the reducer updates the state according to this action.

Mapped to our React application, the state maintained in the store is our app state. A React component serves as the View layer and does two things: render and respond to user operations. So connect is to pass the necessary data in the store as props to the React component for rendering, and wrap the action creator to dispatch an action in response to user operations.

Okay, let’s take a detailed look at what the connect module does. Let’s start with its use. Its API is as follows:

connect([mapStateToProps], [mapDispatchToProps], [mergeProps], [options])

mapStateToProps is a function, and the return value represents the state that needs to be merged into props. The default value is () => ({}), which means nothing is passed.

(state, props) => ({ }) // 通常会省略第二个参数

mapDispatchToProps can be a function. The return value represents the actionCreators that need to merge only props. The actionCreator here should have been packaged with dispatch. It is recommended to use the bindActionCreators function of redux.

(dispatch, props) => ({ // 通常会省略第二个参数
 ...bindActionCreators({
  ...ResourceActions
 }, dispatch)
})

It is more convenient to accept an object directly. At this time, the connect function will convert it into a function. This function is exactly the same as the above example.

mergeProps is used to customize the merge process. The following is the default process. The value of parentProps is the props of the component itself. You can find that if the same name appears on the props of the component, it will be overwritten.

(stateProps, dispatchProps, parentProps) => ({
 ...parentProps,
 ...stateProps,
 ...dispatchProps
})

options have two switches: pure represents whether to turn on optimization. The details will be mentioned below. The default is true. withRef is used to give a ref to the component packaged inside. This ref can be obtained through the getWrappedInstance method. The default is false.

connect returns a function that accepts the constructor of a React component as the connection object, and ultimately returns the connected component constructor.

Then a few questions:

  1. How do React components respond to store changes?

  2. Why does connect selectively merge some props instead of directly passing in the entire state?

  3. What does pure optimize?

We call the function returned by connect Connector. It returns an internal component called Connect. On the basis of packaging the original component, it also listens to Redux internally. Store changes, in order to allow the components wrapped by it to respond to store changes:

trySubscribe() {
 if (shouldSubscribe && !this.unsubscribe) {
  this.unsubscribe = this.store.subscribe(::this.handleChange)
  this.handleChange()
 }
}

handleChange () {
 this.setState({
  storeState: this.store.getState()
 })
}

But usually, what we connect is a Container component, which does not carry all App state, but our handler is responsive All state changes, so what we need to optimize is: when storeState changes, only when we really depend on that part of the state change, will we re-render the corresponding React component. So what is the part we really depend on? It is obtained through mapStateToProps and mapDispatchToProps.

The specific optimization method is to check in shouldComponentUpdate. If shouldComponentUpdate will return true only when the component's own props change, or the result of mapStateToProps changes, or the result of mapDispatchToProps changes, the checking method is Comparison of shallowEqual.

So for a certain reducer:

export default (state = {}, action) => {
 return { ...state } // 返回的是一个新的对象,可能会使组件reRender
 // return state // 可能不会使得组件reRender
}

In addition, when connecting, be careful to map the really needed state or actionCreators to props to avoid unnecessary performance loss.

Finally, according to the connect API, we found that we can use the ES7 decorator function to match the writing method of React ES6:

@connect(
 state => ({
  user: state.user,
  resource: state.resource
 }),
 dispatch => ({
  ...bindActionCreators({
   loadResource: ResourceActions.load
  }, dispatch)
 })
)
export default class Main extends Component {

}

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

related articles:

About JS sorting algorithm summary

How to make a cone using JS canvas

How to implement lazy routing in vue-router Loading

How to implement breakpoint debugging ts file in Angular2

How to implement web page scrolling up

Configuring the folder structure in vue

The above is the detailed content of About connecting react-redux in React and Redux (detailed tutorial). For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Is JavaScript Written in C? Examining the EvidenceIs JavaScript Written in C? Examining the EvidenceApr 25, 2025 am 12:15 AM

Yes, the engine core of JavaScript is written in C. 1) The C language provides efficient performance and underlying control, which is suitable for the development of JavaScript engine. 2) Taking the V8 engine as an example, its core is written in C, combining the efficiency and object-oriented characteristics of C. 3) The working principle of the JavaScript engine includes parsing, compiling and execution, and the C language plays a key role in these processes.

JavaScript's Role: Making the Web Interactive and DynamicJavaScript's Role: Making the Web Interactive and DynamicApr 24, 2025 am 12:12 AM

JavaScript is at the heart of modern websites because it enhances the interactivity and dynamicity of web pages. 1) It allows to change content without refreshing the page, 2) manipulate web pages through DOMAPI, 3) support complex interactive effects such as animation and drag-and-drop, 4) optimize performance and best practices to improve user experience.

C   and JavaScript: The Connection ExplainedC and JavaScript: The Connection ExplainedApr 23, 2025 am 12:07 AM

C and JavaScript achieve interoperability through WebAssembly. 1) C code is compiled into WebAssembly module and introduced into JavaScript environment to enhance computing power. 2) In game development, C handles physics engines and graphics rendering, and JavaScript is responsible for game logic and user interface.

From Websites to Apps: The Diverse Applications of JavaScriptFrom Websites to Apps: The Diverse Applications of JavaScriptApr 22, 2025 am 12:02 AM

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python vs. JavaScript: Use Cases and Applications ComparedPython vs. JavaScript: Use Cases and Applications ComparedApr 21, 2025 am 12:01 AM

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

The Role of C/C   in JavaScript Interpreters and CompilersThe Role of C/C in JavaScript Interpreters and CompilersApr 20, 2025 am 12:01 AM

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript in Action: Real-World Examples and ProjectsJavaScript in Action: Real-World Examples and ProjectsApr 19, 2025 am 12:13 AM

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

JavaScript and the Web: Core Functionality and Use CasesJavaScript and the Web: Core Functionality and Use CasesApr 18, 2025 am 12:19 AM

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

SAP NetWeaver Server Adapter for Eclipse

SAP NetWeaver Server Adapter for Eclipse

Integrate Eclipse with SAP NetWeaver application server.

DVWA

DVWA

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

EditPlus Chinese cracked version

EditPlus Chinese cracked version

Small size, syntax highlighting, does not support code prompt function

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool

SublimeText3 Linux new version

SublimeText3 Linux new version

SublimeText3 Linux latest version