父子组件传值（子组件传递父组件）

父组件js

import React, { Component } from 'react';
import Son from './Son'
import './Father.css'

class Father extends Component {
    constructor(props) {
        super(props);
        this.state = {
            sonValue: null
        }
    }
    
    
    render() {

        let {sonValue} = this.state;

        return (
            <div className="father">
                <h1>我是父组件</h1>
                <p>接收到的数据为：{sonValue}</p>

                <Son onSend={this.handleAction}/>

            </div>
        );
    }

    handleAction = (data)=>{
        console.log('handleAction执行了');
        this.setState({sonValue: data});
    }

}

export default Father;

子组件js

import React, { Component } from 'react';
import './Son.css'

class Son extends Component {

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

    render() {

        // console.log(this.props.onSend);
        // this.props.onSend(1,2,3,4);

        let {inputVal} = this.state;

        return (
            <div className="son">
                <h1>我是子组件</h1>

                <input type="text" value={inputVal} onChange={this.changeAction}/>
                <button onClick={()=>{
                    //调用父组件的函数，传入参数，实现子组件向父组件的传值
                    this.props.onSend(inputVal);
                }}>发送</button>

            </div>
        );
    }

    changeAction = (ev)=>{
        this.setState({inputVal: ev.target.value});
    }
}

export default Son;

父组件css

.father{
    padding: 50px;
    background: lemonchiffon;
}

子组件css

.son{
    padding: 30px;
    background: lightblue;
}