const cssnano = require('cssnano').process const path = require('path') const fs = require('fs') files = fs.readdirSync(path.resolve('lib/themes')) files.forEach(file => { file = path.resolve('lib/themes', file) cssnano(fs.readFileSync(file)).then(result => { fs.writeFileSync(file, result.css) }).catch(e => { console.error(e) process.exit(1) }) })