Bubbling

parent-to-child.js

import React, { Component } from "react";
import logo from "./logo.svg";
import "./App.css";

const Child = ({ onClick }) => <button onClick={onClick}>Click me</button>;

class Parent extends Component {
  field = "hello";

  handleClick = e => {
    console.log(this.field, e);
  };

  render() {
    return <Child onClick={this.handleClick} />;
  }
}

class App extends Component {
  render() {
    return (
      <div className="App">
        <header className="App-header">
          <img src={logo} className="App-logo" alt="logo" />
          <h1 className="App-title">Welcome to React</h1>
        </header>
        <Parent />
      </div>
    );
  }
}

export default App;