react中父组件控制子组件的显示与隐藏

app.js

import React, { Component } from 'react'

import Parent from './components/Parent'

export default class App extends Component {

  render() {

    return (

      <>

        <Parent></Parent>

      </>

    )

  }

}

parent.js

import React, { Component } from 'react'

import Child from './Child'

 

export default class parent extends Component {

  state={

    showChild:true

  }

  f2=()=>{

    this.setState({

      showChild:!this.state.showChild

    })

  }

  render() {

    return (

      <div style={{backgroundColor:'#dfd'}}>

        <h2>父组件</h2>

        <button onClick={this.f2}>显示/隐藏</button>

        {this.state.showChild && <Child></Child>}

      </div>

    )

  }

}

方法一   child.js

import React, { Component } from 'react'

export default class child extends Component {

  state={

    count:0

  }

  f1=()=>{

    this.setState({

      count:this.state.count+1

    })

  }

  constructor(){

    super()

    console.log('组件创建')

  }

  componentDidCatch(){

    console.log('组件挂载')

  }

  render() {

    console.log('组件渲染')

    return (

      <div style={{backgroundColor:'#aaf',margin:'10px',padding:"10px"}}>

        <h3>这里是子组件</h3>

        <button onClick={this.f1}>点击计数器:{this.state.count}</button>

      </div>

    )

  }

}

方法二   child.js

import React, { useState } from 'react'

export default function Child() {

  let [count,f2]=useState(5)

  return (

    <div>

      <h3>子组件</h3>

      <button onClick={()=>f2(count+1)}>点击计数器：{count}</button>

    </div>

  )

}