this.props 是屬性的意思。用于傳遞給控件具體的屬性

import React ,{Component}from 'react'

class MyCommpent2 extends Component{

    render(){
        return(
            <div>
                <div>
                    <div>{this.props.firstName}</div>//得到屬性值是 firstName的值 
                    <div>{this.props.twoName}</div>
                    <div>{this.props.threeName}</div>
                </div>
            </div>
        )
    }
}

export default MyCommpent2 ;

在其調用的地方進行定義屬性值

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import registerServiceWorker from './registerServiceWorker';

import MyCommpent from './MyCommpent'
import MyCommpent2 from './MyCommpent2'


// ReactDOM.render(<App />, document.getElementById('root'));

// ReactDOM.render(<MyCommpent/>,document.getElementById('root'))
ReactDOM.render
(
    <MyCommpent2 firstName='第一個名字' twoName="第二個名字" threeName="第三個名字">   //定義props屬性
  
    </MyCommpent2>,
    document.getElementById('root'))

registerServiceWorker();