functional-update.js

import { useState } from "react";
import { wait } from "./wait";

export function FunctionalUpdates() {
  const [counter, setCounter] = useState(0);

  function handleIncrement() {
    setCounter(counter + 1);
  }

  async function handleIncrementFunctional() {
    await wait({ milisecomds: 2000 });
    setCounter(_counter => _counter + 1);
  }

  return (
    <div>
      <div>Counter value: {counter}</div>
      <button onClick={handleIncrement}>Increment</button>
      <button onClick={handleIncrementFunctional}>Increment functional</button>
    </div>
  );
}