React 父组件触发子组件事件

import React from "react";
import Child from "./component/Child";

class Parent extends React.Component {
  render() {
    return (
      <div>
        我是父组件
        <Child childEvevnt={this.childEvevnt} />
        <button onClick={this.triggerEvevt}>触发子</button>
      </div>
    );
  }
  // 此事件接收子对象
  childEvevnt = childDate => {
    this.$child = childDate;
  };
  // 父组件触发子组件的事件
  triggerEvevt = () => {
    this.$child.alertEvevnt();
  };
}

export default Parent;

import React from "react";
class Child extends React.Component {
  render() {
    return <div>我是子组件</div>;
  }
  componentDidMount() {
    this.props.childEvevnt(this);
  }
  // 父组件要触发的事件
  alertEvevnt = () => {
    alert("父呼唤我呢!!");
  };
}
export default Child;