purgecss.js

const {PurgeCSS} = require('purgecss');
const minify = require('minify');
const scope = require('scope-css');
const fs = require('fs');
const path = require('path');

(new PurgeCSS()).purge({
    content: [
        'app/design/frontend/Magento/ady/**/*.phtml',
        'app/design/frontend/Magento/ady/**/*.html',
        'app/code/Ady/**/*.php'],
    css: ['app/design/frontend/Magento/ady/**/*.css'],
}).then(results => {
    results.forEach(async result => {
        if (result.file.includes('-purged.css')) {
            return true;
        }
        const filename = path.resolve(__dirname, result.file + '-purged.css');
        fs.writeFileSync(filename, result.css);
        fs.writeFileSync(filename, scope(await minify(filename), '.ady'));
    });
    console.log('Done');
});