03.10 - State & Props - Send counter data to parent component (functional components)

App preview:

Project files:

---

src/App.js

import './App.css';
import ParentComponent from './components/ParentComponent';


function App() {
  return (
    <div className="App">
        <p><b>App.js</b> |function|</p>
        <ParentComponent/>
    </div>
  );
}

export default App;

---

src/App.css

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

p{
  margin-top: 6px; 
  margin-bottom: 12px 
}

---

---

src/components/ParentComponent.jsx

import React, { useState } from "react"
import ChildComponent from "./ChildComponent"
import "./ParentComponent.css"

function ParentComponent(){
    const [count, setCounter] = useState(0);

    const updateCounterList = () => {
        setCounter(count + 1)
    }

    return(
        <div className="ParentComponent">
            <p><b>ParentComponent.jsx</b> |function|</p>
            <ChildComponent updateCounterList={()=>{updateCounterList()}}/>
            <p>Click Counter value is {count}.</p>
        </div>
    )
}

export default ParentComponent

---

src/components/ParentComponent.css

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

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

---

---

src/components/ChildComponent.jsx

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

function ChildComponent (props) {

    const handleClick = () => {
        props.updateCounterList();
    }

    return (
        <div className="ChildComponent">
            <p><b>ChildComponent.jsx</b> |function|</p>
            <button onClick={()=>{handleClick()}}>Add 1</button>
        </div>
    );
}

export default ChildComponent;

---

src/components/ChildComponent.css

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

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