React 父子元件通信

1、子元件調用父元件方法

父元件html

<div>
    <Chlid link={this.fn()} />
</div>      

父元件js

fn= e => {
   console.log(e)  //123
  };      

子元件html

<div onClick={() => {
  this.props.link(123);
}}>點選事件</div>      

<div>
    <Chlid link={(e) => {
        this.child = e;
    }} 
/></div>

<div onClick={() => {
     this.child.fn(123);
}}>點選事件</div>      

componentDidMount(){
    this.props.link(this)
}

fn= (e) => {
    console.log(e);
};