build.js

const fs = require('fs-extra'),
	path = require('path'),
	chalk = require('chalk'),
	mkdirp = require('mkdirp'),
	mkdirpSync = require('mkdirp-sync'),
	commander = require('commander'),
	pkg = require('./package.json'),
	
	config = pkg.config,
	themeName = config.theme_name,
	pluginName = config.plugin_name || config.theme_name,
	siteIsVIP = config.vip,
	buildParent = path.resolve(`dist`),
	sourceParent = path.resolve(`src`);

commander.version(pkg.version)
	.option('-k, --keep [keep]', 'does clean the build folder if it already exists', false)
	.parse(process.argv);

const keep = !!commander.keep;

let sourceFolders = ['theme/dist', 'themes', 'plugin/dist', 'plugins', 'mu-plugins'],
	buildFolders = ['themes', 'themes', 'plugins', 'plugins', 'mu-plugins'];

if (siteIsVIP) {
	const vipFolders = [
		'client-mu-plugins',
		'images',
		'languages',
		'private',
		'vip-config',
	];

	sourceFolders = sourceFolders.concat(vipFolders);
	buildFolders = buildFolders.concat(vipFolders);
}
if (fs.existsSync(buildParent) && !keep) {
	console.log(chalk.yellow('cleaning build folder'), buildParent);
	fs.removeSync(buildParent);
	mkdirpSync(buildParent);
}

for (const index in sourceFolders) {
	let sourceName = sourceFolders[index],
		buildName = buildFolders[index],
		sourceFolder = path.join(sourceParent, sourceName),
		buildFolder = path.join(buildParent, buildName);

			if (fs.existsSync(sourceFolder)) {
			fs.readdir(sourceFolder, function (err, files) {

			if (err) console.error(err)
			else {
				if (files.length) {

					// Aptly name the theme or plugin
					if (sourceName == 'theme' || sourceName == 'theme/dist') {
						buildFolder = path.join(buildFolder, themeName);
					} else if (sourceName == 'plugin' || sourceName == 'plugin/dist') {
						buildFolder = path.join(buildFolder, pluginName);
					}

					mkdirp(buildFolder, function (err) {

						if (err) console.error(err);
						else {
							fs.copy(sourceFolder, buildFolder, { filter: (file) => {
								if (file.indexOf('node_modules') !== -1) return false;
								else return true;
							} }, function (err) {

								if (err) return console.error(err);
								else {
									console.log(chalk.green(`${sourceName} copied to the build folder`), buildFolder);
								}
							});
						}
					});
				}
			}

		});
	}
}