client-auth.js

const axios = require("axios");

axios.defaults.baseURL = "http://localhost:4000/";

const login = async (email, password) => {
  const axiosResponse = await axios.post('/', {
    query: `mutation Login {
      login(email: "${email}", password: "${password}") {
        token
      }
    }`
  });

  const graphqlQueryData = axiosResponse.data;
  const authenticationToken = graphqlQueryData.data.login.token;

  axios.defaults.headers.common['Authorization'] = `Bearer ${authenticationToken}`;
}

const posts = async () => {
  const axiosResponse = await axios.post('/', {
    query: `query FetchPosts {
      posts {
        title
      }
    }`
  });

  const graphqlQueryData = axiosResponse.data;
  const posts = graphqlQueryData.data.posts;

  return posts;
}

const main = async () => {
  await login("foo@example.com", "bar");
  await posts();
}

main();