hook-react-example

app.jsx

//"react": "^16.7.0-alpha.0"
//"react-dom": "^16.7.0-alpha.0"

import React, { useState } from "react";
import ReactDOM from "react-dom";
import "./styles.css";

function App() {
  const [number, setNumber] = useState(0);  
  
  const sum = v => setNumber(number + 1);
  const sub = v => setNumber(number - 1);

  return (
    <div className="App">
      <button onClick={sum}>+</button>
      <button onClick={sub}>-</button>
      <h1>{number}</h1>
    </div>
  );
}

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);