父组件向子组件传输用prop，那如果子组件向父组件传输怎么传呢
子组件通过click事件点击，把回调里面的flag变量里面值想传给父组件，怎么传呢

class Child_1 extends React.Component {//子组件
    constructor(props) {
        super(props);
        this.state = {
            getName: this.props.name,
            getAge: this.props.age,
        }
    }
    click = () => {
        let flag = 'test';
    }
    render() {
        const {getName, getAge} = this.state;
        return (
            <div>
                <p>{`姓名：${getName}`}</p>
                <p>{`年龄：${getAge}`}</p>
                <div onClick={this.click}>click me</div>
            </div>
        )
    }
}
export default Child_1;

import Child_1 from './Child_1';
class Parent extends React.Component {//父组件
    constructor(props) {
        super(props);
        this.state = {}
    }
    componentDidMount() {

    }
    render() {
        return (
            <div>
                <Child_1 name="张三" age="25"/>
            </div>
        )
    }
}
export default Parent;