Example config your Laravel project with two builds (public and admin)

1. Create Laravel Project

   laravel new my-project
   cd my-project
   # remove existing frontend scaffold
   rm -rf package.json webpack.mix.js yarn.lock resources/js resources/sass public/js public/css

2. Create a Vue CLI 4 project in the Laravel '/resources/frontend/'

   cd resources/frontend
   vue create app
   #and (if you need admin build)
   vue create admin

3. Configure Vue CLI 4 project

   Create /resources/frontend/app/vue.config.js:

   module.exports = {
    devServer: {
    proxy: 'http://laravel.test'
    },
    // output built static files to Laravel's public dir.
    // note the "build" script in package.json needs to be modified as well.
    outputDir: '../../../public/assets/app',
    publicPath: process.env.NODE_ENV === 'production'
    ? '/assets/app/'
    : '/',
    // modify the location of the generated HTML file.
    indexPath: process.env.NODE_ENV === 'production'
    ? '../../../resources/views/app.blade.php'
    : 'index.html'
   }

   Edit /resources/frontend/app/package.json

   "scripts": {
    "serve": "vue-cli-service serve",
   - "build": "vue-cli-service build",
   + "build": "rm -rf ../../../public/assets/app/{js,css,img} && vue-cli-service build --no-clean",
    "lint": "vue-cli-service lint"
   },

   and (if you need admin build)

   Create /resources/frontend/admin/vue.config.js:

   module.exports = {
    // proxy API requests to Valet during development
    devServer: {
    proxy: 'http://laravel.test/admin'
    },
    // output built static files to Laravel's public dir.
    // note the "build" script in package.json needs to be modified as well.
    outputDir: '../../../public/assets/admin',
    publicPath: process.env.NODE_ENV === 'production'
    ? '/assets/admin/'
    : '/admin',
    // modify the location of the generated HTML file.
    // make sure to do this only in production.
    indexPath: process.env.NODE_ENV === 'production'
    ? '../../../resources/views/admin.blade.php'
    : 'index.html'
   }

   Edit /resources/frontend/admin/package.json

   "scripts": {
    "serve": "vue-cli-service serve",
   - "build": "vue-cli-service build",
   + "build": "rm -rf ../../../public/assets/admin/{js,css,img} && vue-cli-service build --no-clean",
    "lint": "vue-cli-service lint"
   },

4. Configure Laravel routes for SPA.

   routes/web.php

   <?php
   // For admin application
   Route::get('/admin{any}', 'FrontendController@admin')->where('any', '.*');
   // For public application
   Route::any('/{any}', 'FrontendController@app')->where('any', '^(?!api).*$');

   app/Http/Controllers/FrontendController.php

   <?php
   namespace App\Http\Controllers;
   use Illuminate\Http\Request;
   class FrontendController extends Controller
   {
    // For admin application
    public function admin()
    {
    return view('admin');
    }
    // For public application
    public function app()
    {
    return view('app');
    }
   }

5. Change base: process.env.BASE_URL in router.js for correct Vue Router

   // For App
   base: '/',
   // For Admin
   base: '/admin/',

6. Add package.json in root (if you want use yarn run in root)

   {
    "name": "laravel",
    "version": "0.2.0",
    "private": true,
    "scripts": {
    // For public application
    "prepare:app": "cd resources/frontend/app && yarn install",
    "serve:app": "cd resources/frontend/app && yarn run serve",
    "build:app": "cd resources/frontend/app && yarn run build",
    "lint:app": "cd resources/frontend/app && yarn run lint",
    "test:app": "cd resources/frontend/app && yarn run test:unit",
    // For admin application
    "prepare:admin": "cd resources/frontend/admin && yarn install",
    "serve:admin": "cd resources/frontend/admin && yarn run serve",
    "build:admin": "cd resources/frontend/admin && yarn run build",
    "lint:admin": "cd resources/frontend/admin && yarn run lint",
    "test:admin": "cd resources/frontend/admin && yarn run test:unit"
    }
   }