aa.js

import logo from './logo.svg';
import './App.css';
import {ToastContainer, toast} from 'react-toastify';
import 'react-toastify/dist/ReactToastify.css';
import {useEffect} from "react";

function App() {

   useEffect(() => {
       async function fetchData() {
           try {
               let version = localStorage.getItem("notification-version");
               version = version ? version : 0;
               const response = await fetch("REPLACE_UPSTASH_REDIS_REST_URL/zrevrangebyscore/messages/+inf/" + version + "/WITHSCORES/LIMIT/0/1", {
   headers: {
       Authorization: "Bearer REPLACE_UPSTASH_REDIS_REST_TOKEN"
   }
});
               const res = await response.json();
               const v = parseInt(res.result[1]);
               if (v) {
                   localStorage.setItem("notification-version", v + 1)
               }
               toast(res.result[0]);
           } catch (e) {
               console.error(e);
           }
       };
        fetchData();
   });

   return (
       <div className="App">
           <header className="App-header">
               <img src={logo} className="App-logo" alt="logo"/>
               <p>
                   Edit <code>src/App.js</code> and save to reload.
               </p>
               <a
                   className="App-link"
                   href="https://reactjs.org"
                   target="_blank"
                   rel="noopener noreferrer"
               >
                   Learn React
               </a>
           </header>
           <ToastContainer/>
       </div>
   );
}

export default App;