Extending Dr. Axel Rauschmayer's RESTful web service example

proxies.js

// Source http://exploringjs.com/es6/ch_proxies.html#_accessing-a-restful-web-service-method-calls

const gitHubService = createWebService('http://api.github.com');

gitHubService.feeds.get().then(data => {
  console.log(data.timeline_url);
});

gitHubService.users.blrobin2.get().then(data => {
  console.log(data.avatar_url);
});

gitHubService.search.issues.params({q: 'test'}).get().then(data => {
  console.log(data.items);
});

function createWebService(baseUrl) {
  const proxy = new Proxy({
    endpoint: '',
    params(obj) {
      Object.keys(obj).forEach(prop => {
        if (this.endpoint.includes('?')) {
          this.endpoint += '&';
        } else {
          this.endpoint += '?';
        }
        this.endpoint += `${prop}=${obj[prop]}`;
      });
      
      return proxy;
    },
    get() {
      const endpoint = this.endpoint;
      this.endpoint = '';
      return httpGet(`${baseUrl}/${endpoint}`);
    }
  }, {
    get(target, property) {
      if (target.hasOwnProperty(property)) {
        return target[property];
      }
      if (target.endpoint) {
        target.endpoint += `/${property}`;
      } else {
        target.endpoint = property;
      }
      
      return proxy;
    }
  });
  
  return proxy;
}

function httpGet(url) {
  return fetch(url).then(data => data.json());
}