apollo-client.js

import ApolloClient, { createNetworkInterface } from 'apollo-client';

const networkInterface = createNetworkInterface('/graphql');

networkInterface.use({
  applyMiddleWare(req, next) => {
    if (!req.options.header) {
      req.options.header = {};  // Create the header object if needed.
    }
    req.options.header.authorization = localStorage.getItem('token') ? localStorage.getItem('token') : null;
    next();
  }
});

const client = new ApolloClient({
  networkInterface,
});