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Introduction to React component communication (code example)

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Release: 2019-04-03 09:43:49
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This article brings you an introduction to React component communication (code examples). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

I have been free to study the React framework by myself recently. All the problems and experiences during the self-study process will be recorded here. I hope it can help students who are learning the React framework. Without further ado, let’s talk about the code.
First pass from parent to child:

import React, { Component } from 'react';
import Com1 from './componments/com1'

class App extends Component {
  constructor(props){
    super(props)
    this.state = {
      arr: [{
          "userName": "fangMing", "text": "123333", "result": true
      }, {
          "userName": "zhangSan", "text": "345555", "result": false
      }, {
          "userName": "liSi", "text": "567777", "result": true
      }, {
          "userName": "wangWu", "text": "789999", "result": true
      },]
    };
    this.foo = "我来自父组件"  //这个也是父传子方法,可能初学者有点迷,刚开始我也用来和arr = {this.state.arr}做区分
  };
  render() {
    return (
      <div>
        <header>
          <img  alt="Introduction to React component communication (code example)" >                    
        </header>
        <com1></com1>
      </div>
    );
  }
}
export default App;
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Child component:

import React, { Component } from 'react';

class Ele extends Component{
    constructor(props){
       super(props)  
    };
    render(){
        return (
           <div>
               <h1>Hello, {this.props.age}</h1>
               <p>{this.props.fn}</p>
               <ul>
                    {
                        this.props.arr.map(item => { //这个地方通过this.props.arr接收到父组件传过来的arr,然后在{}里面进行js的循环
                            return (
                                <li>
                                    {item.userName} 评论是:{item.text}
                                </li>
                            )
                        })
                    }
                </ul>
           </div>
        );
    };
}

export default Ele;
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The result shows:

Introduction to React component communication (code example)

The above is the parent The main method of passing values ​​​​to children is to use props to pass values. Let’s take a look at passing from child to parent.

Passing from child to parent:
First is the child component:

import React, { Component } from 'react';

class Ele extends Component{
    constructor(props){
       super(props);
       this.state = ({
            childText: "我来自子组件"
       })  
    };
    clickFun(text) {  //定义触发的方法
        this.props.pfn(text)//这个地方把值传递给了props的事件当中
    }
    render(){
        return (
           <div>               
                {/* 通过事件进行传值,如果想得到event,可以在参数最后加一个event,
                这个地方还是要强调,this,this,this */}
                <button>
                    传值
                </button>
           </div>
        );
    };
}

export default Ele;
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Parent component:

import React, { Component } from 'react';
import Com1 from './componments/com1'

class App extends Component {
  constructor(props){
    super(props)
    this.state = {
      parentText: "现在是父组件",     
  };
  fn(data) {
    this.setState({
        parentText: data //把父组件中的parentText替换为子组件传递的值
    },() =>{
       console.log(this.state.parentText);//setState是异步操作,但是我们可以在它的回调函数里面进行操作
    });
  };
  render() {
    return (
      <div>
        <com1></com1> {/*通过绑定事件进行值的运算,这个地方一定要记得.bind(this),不然会报错,切记切记,因为通过事件传递的时候this的指向已经改变 */}
        <p>text is {this.state.parentText}</p>
      </div>
    );
  }
}
export default App;
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The above is the method of value transfer between parent and child components. Please correct me if there are any mistakes
I haven’t learned about value transfer between sibling components yet. I will update it after learning about value transfer between sibling components

[Related recommendations: React video tutorial]

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source:segmentfault.com
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