title: Laravel/Vuejs app does not update after deploying to Heroku
body: <p>I have a Laravel/Vuejs app that works well on localhost. After deploying to Heroku, I realized that styles added to app.scss does not compile into my public/css file, thus have no effect. Also, modifications to my vuejs components does not update the app after I push to Heroku with <code>git push heroku master</code>.</p>
  
  <p>I have added heroku/nodejs buildpack on my heroku dashboard. Here is my webpack.mix.js file content;</p>
  
  <pre><code>const mix = require('laravel-mix');
  
  mix.js('resources/js/app.js', 'public/js')
      .sass('resources/sass/app.scss', 'public/css');
  
  mix.browserSync({
      proxy: 'localhost:8000'
  });
  </code></pre>
  
  <p>My package.json file:</p>
  
  <pre><code>"scripts": {
          "dev": "npm run development",
          "development": "cross-env NODE_ENV=development node_modules/webpack/bin/webpack.js --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js",
          "watch": "npm run development -- --watch",
          "watch-poll": "npm run watch -- --watch-poll",
          "hot": "cross-env NODE_ENV=development node_modules/webpack-dev-server/bin/webpack-dev-server.js --inline --hot --config=node_modules/laravel-mix/setup/webpack.config.js",
          "prod": "npm run production",
          "production": "cross-env NODE_ENV=production node_modules/webpack/bin/webpack.js --no-progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js",
          "heroku-prebuild": "export NPM_CONFIG_PRODUCTION=false; export NODE_ENV=; NPM_CONFIG_PRODUCTION=false NODE_ENV=development npm install --only=dev --dev",
          "heroku-postbuild": "export NPM_CONFIG_PRODUCTION=true; export NODE_ENV=production"
      },
  </code></pre>
  
  <p>When i add a postinstall key to scripts like so:</p>
  
  <pre><code>"postinstall": "npm run prod"
  </code></pre>
  
  <p>I get an error on deploy:</p>
  
  <pre><code>remote:        npm ERR! errno 2
  remote:        npm ERR! undefined postinstall: `npm run prod`
  remote:        npm ERR! Exit status 2
  remote:        npm ERR!
  remote:        npm ERR! Failed at the undefined postinstall script.
  remote:        npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
  remote:
  remote:        npm ERR! A complete log of this run can be found in:
  remote:        npm ERR!     /tmp/npmcache.a6MDK/_logs/2019-11-28T08_41_39_044Z-debug.log
  remote:
  remote: -----&gt; Build failed
  remote:
  remote:        We're sorry this build is failing! You can troubleshoot common issues here:
  remote:        https://devcenter.heroku.com/articles/troubleshooting-node-deploys
  remote:
  remote:        Some possible problems:
  remote:
  remote:        - Node version not specified in package
  remote:          https://devcenter.heroku.com/articles/nodejs-support#specifying-a-node-js-version
  remote:
  remote:        Love,
  remote:        Heroku
  remote:
  remote:  !     Push rejected, failed to compile Node.js app.
  remote:
  remote:  !     Push failed
  remote: Verifying deploy...
  remote:
  remote: !       Push rejected to blemademo.
  remote:
  To https://git.heroku.com/blemademo.git
   ! [remote rejected]   master -&gt; master (pre-receive hook declined)
  error: failed to push some refs to 'https://git.heroku.com/blemademo.git'
  </code></pre>