React useCallback

useCallback.js

import React, { useState } from "react";
import Child from "./Child";
import "./styles.css";

const MyReact = {
  storage: {},
  myCallback: function(fn) {
    if (this.storage.fn === undefined) {
      this.storage.fn = fn;
    }
    return this.storage.fn;
  }
};

export default function App() {
  const [count, setCount] = useState(0);
  const sayHello = MyReact.myCallback(() => {
    setCount(prev => (prev += 1));
  });

  return (
    <div className="App">
      {console.log("parent render")}
      <h1>Hello {count}}</h1>
      <Child sayHello={sayHello} />
      <h2>Start editing to see some magic happen!</h2>
    </div>
  );
}