jku-iis-project-mawen/src/index.js

import React from 'react';
import ReactDOM, {hydrate, render} from 'react-dom';
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';

const rootElement = document.getElementById("root");
if (rootElement.hasChildNodes()) {
  hydrate(<App />, rootElement);
} else {
  render(<App />, rootElement);
}