react父子组件通信父传子、子传父

理论性的知识咋们后期加，主要实现下最基本的父子互传。
直接附代码
父组件

import React, { Component } from 'react';
import Child from '../children';
export default class index extends Component {

  constructor(props) {
    super(props);
    this.state = {
      count: 0,
      visible: true
    };
  }
 
  handelClick() {
    console.log(this);
  }

  fn(data) {
    // console.log(data,'data');
    this.setState({
      count: data
    }, () => {
      console.log(this.state.count,'父组件');
    });
  }

  

  render() {
    return (
      <div style={{background:'green'}}>
        {this.state.count}
        父组件
        <Child count={this.state.count} pfn={this.fn.bind(this)}></Child>
        <button onClick={this.handelClick.bind(this)}>点击</button>
      </div>
    );
  }
}

子组件

import React, { Component } from 'react';

export default class index extends Component {

  constructor(props) {
    super(props);
    this.state = {
      count: props.count
    };
  }

  static getDerivedStateFromProps(nextProps, prevState) {
    if (nextProps.count !== prevState.count) {
      return {
        count: nextProps.count
      };
    }
    return null;
  }

  handleC(text) {
    // console.log(text);
    this.props.pfn(text);
  }

  render() {
    return (
      <div style={{border: 'solid 1px #ccc', margin: '0 20px'}}>
        这是子组件
        {this.state.count}
        <button style={{width:'200px', height:'100px'}} onClick={this.handleC.bind(this, 2)}>点击向父组件传递</button>
      </div>
    );
  }
}