Authentication Link Example from https://www.apollographql.com/docs/react/recipes/authentication.html#Header

AuthLinkExampleFromApolloDocs.js

// Authentication Link Example from https://www.apollographql.com/docs/react/recipes/authentication.html#Header

import { ApolloClient } from 'apollo-client';
import { createHttpLink } from 'apollo-link-http';
import { setContext } from 'apollo-link-context';
import { InMemoryCache } from 'apollo-cache-inmemory';

const httpLink = createHttpLink({
  uri: '/graphql',
});

const authLink = setContext((_, { headers }) => {
  // get the authentication token from local storage if it exists
  const token = localStorage.getItem('token');
  // return the headers to the context so httpLink can read them
  return {
    headers: {
      ...headers,
      authorization: token ? `Bearer ${token}` : null,
    }
  }
});

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