twoFuncComp.js

import React, { useState, Fragment } from "react";

const WelcomeMessage = ({ user }) => {
  console.log("render WelcomeMessage");
  return <label>Hello {user}</label>;
};

const Page = () => {
  const [user, setUser] = useState();
  console.log("render Page");

  return (
    <Fragment>
      <WelcomeMessage user={user} />
      <button onClick={() => setUser("Jack")}>
        Set user
      </button>
    </Fragment>
  );
};