Directive class extending with ECMAScript 6

autocomplete.controller.js

class AutocompleteController {
  constructor () {
    'ngInject';
  }

  querySearch (query) {
    return this.service.search(query);
  }

  selectedItemChange(item) {
    this.item = item;
  }
}

export default AutocompleteController;

autocomplete.directive.js

class AutocompleteDirective {
  constructor (directive) {
    'ngInject';

    this.directive = {
      restrict: 'E',
      scope: {
        placeholder: '@'
      },
      controllerAs: 'ctrl',
      bindToController: true
    };
  }
}

export default AutocompleteDirective;

company.directive.js

import AutocompleteDirective from '../autocomplete.directive';
import AutocompleteController from '../autocomplete.controller';

class CompanyAutocompleteDirective extends AutocompleteDirective {
  constructor () {
    'ngInject';

    super();

    this.directive = angular.merge(this.directive, {
      templateUrl: 'app/components/autocomplete/company/company.html',
      controller : CompanyAutocompleteController,
      scope      : {
        item       : '=company'
      },
    });

    return this.directive;
  }
}

class CompanyAutocompleteController extends AutocompleteController {
  constructor ($log, companyService) {
    'ngInject';

    super();

    this.service   = companyService;
  }
}

export default CompanyAutocompleteDirective;

company.service.js

class CompanyService {
  constructor ($http, apiService) {
    'ngInject';

    this.$http   = $http;
    this.$log    = $log;
    this.apiHost = `${apiService.url}/companies`;
  }

  search (query) {
    return this.$http.get(`${this.apiHost}/search?q=${query}`)
      .then((response) => {
        return response.data;
      })
      .catch((error) => {
        this.$log.error(`XHR Failed for CompanyService.search\n${angular.toJson(error.data, true)}`);
      });
  }
}

export default CompanyService;

index.module.js

import CompanyService from '../app/components/autocomplete/company/company.service';

angular.module('app', ['ui.router', 'ngMaterial'])
  .service('companyService', CompanyService)
  .directive('companyAutocomplete', () => new CompanyAutocompleteDirective());