详解React的组件通讯

class Parent extends React.Component {
    state = { lastName: '王' }
    render() {
        return (
            <div>
                传递数据给子组件：<Child name={this.state.lastName} />
            </div>
        )
    }
}

function Child(props) {
	return <div>子组件接收到数据：{props.name}</div>
}

class Parent extends React.Component {
    state: {
      num: 100
    }
    f = (num) => {
        console.log('接收到子组件数据', num)
    }
    render() {
        return (
            <div>
            	子组件：<Child f={this.f} />
            </div>
        )
    }
}

class Child extends React.Component {
    handleClick = () => {
      // 调用父组件传入的props，并传入参数
    	this.props.f(100)
    }
    return (
    	<button onClick={this.handleClick}>点我，给父组件传递数据</button>
    )
}

import React, { Component } from 'react'
import ReactDOM from 'react-dom'
import Jack from './Jack'
import Rose from './Rose'
class App extends Component {
  // 1. 状态提升到父组件
  state = {
    msg: '',
  }
  render() {
    return (
      <div>
        <h1>我是App组件</h1>
        <Jack say={this.changeMsg}></Jack>
        {/* 2. 把状态给子组件显示 */}
        <Rose msg={this.state.msg}></Rose>
      </div>
    )
  }
  changeMsg = (msg) => {
    this.setState({
      msg,
    })
  }
}
// 渲染组件
ReactDOM.render(<App />, document.getElementById('root'))

import React, { Component } from 'react'
export default class Jack extends Component {
  render() {
    return (
      <div>
        <h3>我是Jack组件</h3>
        <button onClick={this.say}>说</button>
      </div>
    )
  }
  say = () => {
    this.props.say('you jump i look')
  }
}

import React, { Component } from 'react'
export default class Rose extends Component {
  render() {
    return (
      <div>
        <h3>我是Rose组件-{this.props.msg}</h3>
      </div>
    )
  }
}

import { createContext } from 'react'
const { Provider, Consumer } = createContext()

return (
  <Provider value={ 这里放要传递的数据 }>
  	<根组件的内容/>
  </Provider>
)

return (
	<Consumer>
  	{
      （data） => {
      	// 这里的形参data 就会自动接收Provider中传入的数据
        // console.log(data)
      	return <组件的内容>
    	}
    }
  </Consumer>
)

import { createContext } from 'react'
const { Provider, Consumer } = createContext()
export { Consumer, Provider }

import { Provider } from './context'
render () {
    return (
      <Provider value={{ num: this.state.num }}>
        <div>
          根组件, num: {this.state.num}
          <Parent />
          <Uncle />
        </div>
      </Provider>
    )
  }

import React from 'react'
import { Consumer } from './context'
export default class Uncle extends React.Component {
  render () {
    return (
      <Consumer>
        {(data) => {
          return <div>我是Uncle组件, {data.num}</div>
        }}
      </Consumer>
    )
  }
}