import React from "react"
import ParentComponent from './components/ParentComponent';
import './App.css';

class App extends React.Component{
  constructor(props){
    super(props);
    this.state = {
      count: 0,
    }
  }

  handleClick = () => {
    this.setState((prevState)=>({count: prevState.count + 1}))
  }

  render(){
    return(
      <div className="App">
        <h1>App.js</h1>
        <button onClick={()=>{this.handleClick()}}>Click Me</button>
        <ParentComponent count={this.state.count}/>
      </div>

    )
  }
}

export default App;

.App{
  background-color: lightskyblue;
  padding: 20px 10px;
}

h1{
  margin-top: 0px; 
  margin-bottom: 6px 
}

button{
  margin-bottom: 6px; 
}

import React from "react"
import ChildComponent from "./ChildComponent"
import "./ParentComponent.css"

class ParentComponent extends React.Component{
    constructor(props){
        super(props);
    }

    render(){
        const {count} = this.props

        return(
            <div>
                <div className="ParentComponent">
                    <h2>ParentComponent.jsx</h2>
                    <ChildComponent count={count}/>
                </div>

            </div>
        )
    }

}

export default ParentComponent

.ParentComponent{
    background-color: lightsalmon;
    padding: 10px 10px;
}

h2{
    margin-top: 0px; 
    margin-bottom: 6px 
}

import React from "react";
import "./ChildComponent.css"

class ChildComponent extends React.Component{
    render(){
        const {count} = this.props;

        return (
            <div className="ChildComponent">
                <h3>ChildComponent.jsx</h3>
                <p>The value of count is {count}.</p>
            </div>
        );
    }
}

export default ChildComponent;

.ChildComponent{
    background-color: lightgreen;
    padding: 10px 10px;
}

h3{
    margin-top: 0px; 
    margin-bottom: 6px 
}