Api/routes/web.php

<?php

use Illuminate\Support\Facades\Route;

/*
|--------------------------------------------------------------------------
| Web Routes
|--------------------------------------------------------------------------
|
| Here is where you can register web routes for your application. These
| routes are loaded by the RouteServiceProvider within a group which
| contains the "web" middleware group. Now create something great!
|
*/

Route::get('/', function () {
    return view('welcome');
});

Route::group(['namespace' => 'Costco', 'prefix' => 'costco'], function () {
    Route::get('/', 'CostcoController@index');
    Route::get('serviceworker.js', 'CostcoController@serviceWorker');
});