接下来JS，React使子组件告诉父组件呈现什么

// 父组件
class ParentComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      content: ""
    };
  }

  handleChildCallback = (content) => {
    this.setState({ content });
  }

  render() {
    return (
      <div>
        <ChildComponent onCallback={this.handleChildCallback} />
        <div>{this.state.content}</div>
      </div>
    );
  }
}

// 子组件
class ChildComponent extends React.Component {
  handleClick = () => {
    const content = "这是子组件传递给父组件的内容";
    this.props.onCallback(content);
  }

  render() {
    return (
      <button onClick={this.handleClick}>告诉父组件呈现内容</button>
    );
  }
}