ApolloProvider.js

import React from "react";
import App from "./App";
import ApolloClient from "apollo-client";
import { ApolloProvider } from "@apollo/react-hooks";
import { createHttpLink } from "apollo-link-http";
import { InMemoryCache } from "apollo-cache-inmemory";
import { setContext } from "apollo-link-context";
import { onError } from "apollo-link-error";

const httpLink = createHttpLink({ uri: "http://localhost:5001" });

const authLink = setContext(() => {
  const token = localStorage.getItem("jwtToken");
  return {
    headers: {
      Authorization: token ? `Bearer ${token}` : ""
    }
  };
});

const errorLink = onError(({ graphQLErrors, operation, forward }) => {
  if (graphQLErrors) {
    for (let err of graphQLErrors) {
      switch (err.extensions.code) {
        case "UNAUTHENTICATED":
          window.location.href = "/login";
          // retry the request, returning the new observable
          return forward(operation);
      }
    }
  }
});

const link = errorLink.concat(authLink);

const client = new ApolloClient({
  link: link.concat(httpLink),
  cache: new InMemoryCache()
});

export default (
  <ApolloProvider client={client}>
    <App />
  </ApolloProvider>
);