Build multiple apps' sass templates with webpack

.gitignore

/node_modules
/public/hot
/public/storage
/storage/*.key
/vendor
.env
.env.backup
.phpunit.result.cache
docker-compose.override.yml
Homestead.json
Homestead.yaml
npm-debug.log
yarn-error.log
/.idea
/.vscode

# allow only minified files
public/assets/css/**/*.css
!public/assets/css/**/*.min.css

webpack.mix.js

require('laravel-mix-purgecss');

const mix = require('laravel-mix');
const minifier = require('minifier');
const fs = require('fs');

/*
 |--------------------------------------------------------------------------
 | Mix Asset Management
 |--------------------------------------------------------------------------
 |
 | Mix provides a clean, fluent API for defining some Webpack build steps
 | for your Laravel applications. By default, we are compiling the CSS
 | file for the application as well as bundling up all the JS files.
 |
 */

mix.setPublicPath('public/assets');

mix.js('resources/js/app.js', 'js');

/**
 * Build resource/sass templates and minify outputs
 */
const buildAppStyles = function (sassRootPath) {
    // find app folder in given root folder
    const appSassFolders = fs.readdirSync(sassRootPath).filter(function (item) {
        return fs.statSync(`${sassRootPath}/${item}`).isDirectory();
    });

    appSassFolders.forEach((folder) => {
        const sassFolder = `resources/sass/${folder}/pages`,
            cssFolder = `public/assets/css/${folder}`;

        // get page sass files
        var sassFiles = fs.readdirSync(sassFolder).filter((file) => {
            return fs.statSync(`${sassFolder}/${file}`).isFile();
        });

        sassFiles.forEach((file) => {
            let filename = file.replace('.scss', ''),
                cssOutputFilename = `${cssFolder}/${filename}.css`;

            // build and then minify for production
            // purgetCss is comes with 'laravel-mix-purgecss' package
            mix.sass(`${sassFolder}/${file}`, cssOutputFilename).purgeCss().then(() => {
                minifier.minify(cssOutputFilename);
            });
        });
    });
};

buildAppStyles('resources/sass/');