// Copy over native stuff fs.readdir('./src', (err, files) => { files .filter(filename => !/native/.test(filename)) .forEach(filename => { let nativeName = filename .split('.') .insert(1, 'native') .join('.') if (files.includes(nativeName)) { fs.createReadStream(path.join('./src', nativeName)) .pipe(fs.createWriteStream(path.join('./dist/native', filename))) } else { fs.createReadStream(path.join('./src', filename)) .pipe(fs.createWriteStream(path.join('./dist/native', filename))) } }) })