RestClient.js

const factorEndpoint = (baseUrl) => {
  const endpoint = (id) => {
    return createApi(`${baseUrl}/${id}`);
  }
  Object.assign(endpoint, {
    get(id){
      const url = id ? `${baseUrl}/${id}` : baseUrl;
      console.log('GET on', url);
    },
    delete(){},
    post(id) {
      const url = id ? `${baseUrl}/${id}` : baseUrl;
      console.log('POST on', url);
    },
    put() {},
    patch() {}
  });
  return endpoint;
}

const createApi = (baseUrl) => {
  const endpoint = factorEndpoint(baseUrl);
  return new Proxy(endpoint, {
    get(target, key) {
      if (target[key]) {
        return target[key];
      }
      return createApi(`${baseUrl}/${key}`);
    }
  });
};

const api = createApi('http://localhost');

// GET /people
api.people.get();
// GET /people/12
api.people.get(12);
// GET /people/14/hobbies
api.people(14).hobbies.get();
// POST /entities/companies/14/assets/11/actions/sell
api.entities.companies(14).assets(11).actions.sell.post();