React.js 簡単なカウンターを作成する

> yarn global add create-react-app
> npx create-react-app react-test

> npm install -g yarn

> cd react-app

import { useState } from "react";
import logo from "./logo.svg";
import "./App.css";

function App() {
  const [count, setCount] = useState(0);

  return (
    <div className="App">
      <header className="App-header">
        <img src={logo} className="App-logo" alt="logo" />

        <button onClick={() => setCount(count + 1)}>カウント</button>

        <p>{count}</p>
      </header>
    </div>
  );
}

export default App;

> yarn start