Example of an API class that helps with server communication

api-class.js

const SERVER_URL = "https://donamaid.herokuapp.com";

class API {
  constructor() {
    this.token = null;
    this.currentUser = null;

    this.defaultParams = this.defaultParams.bind(this);
    this.fetchJSON = this.fetchJSON.bind(this);
    this.authenticate = this.authenticate.bind(this);
    this.get = this.get.bind(this);
    this.post = this.post.bind(this);
  }

  defaultParams() {
    return {
      headers: {
        "Content-Type": "application/json",
        Authorization: `Bearer ${this.token}`
      }
    };
  }

  async authenticate(email, password) {
    const {
      data: { token, account }
    } = await this.post("authentication", {
      email,
      password
    });

    this.token = token;
    this.currentUser = account;
  }

  async fetchJSON(path, options = {}) {
    return (await fetch(`${SERVER_URL}/${path}`, {
      ...this.defaultParams(),
      ...options
    })).json();
  }

  get(path, options = {}) {
    return this.fetchJSON(path, {
      method: "GET",
      ...options
    });
  }

  post(path, body, options = {}) {
    return this.fetchJSON(path, {
      method: "POST",
      body: JSON.stringify(body),
      ...options
    });
  }
}

(async () => {
  const api = new API();
  try {
    await api.authenticate("USER_EMAIL", "USER_PASSWORD");
    const {
      data: {
        attributes: { language, time_zone: timeZone }
      }
    } = await api.get(`accounts/${api.currentUser.id}`);
    console.log(new Date().toLocaleString(language, { timeZone }));
  } catch (e) {
    console.log(e);
  }
})();