Mono - index.tsx

useEffect(() => {
    window.addEventListener('message', function(event) {
      console.log('los evetnos MONOOOO', event)
      if (event.origin === "http://localhost:9000") {
        if (event.data) {
          localStorage.setItem("user", JSON.stringify(event.data));
        } else {
          localStorage.removeItem("user");
        }
      }
    });
  }, [])