index.js

import React from 'react';
import { render } from 'react-dom';
import {
  ApolloClient,
  InMemoryCache,
  ApolloProvider,
} from "@apollo/client";

const client = new ApolloClient({
  uri: 'https://countries.trevorblades.com/',
  cache: new InMemoryCache()
});

function App() {
  return (
    <div>
      <h2>My first Apollo app 🚀</h2>
    </div>
  );
}

render(

  <ApolloProvider client={client}>
    <App />
  </ApolloProvider>,
  document.getElementById('root'),
);