If we need to handle CORS within Express, we can simply write the following (we’ll assume you’ve also added express to your packages)

• yarn add cors

Now our usual Express code with the addition of CORS support

import express from "express";
import cors from "cors";

const app = express();
const server = http.createServer(app);

app.use(cors());

const port = 4000;
server.listen(port, 
  () => console.log(`Server on port ${port}`)
);