code: function _copyPackageJson(from, to) {
    return new Promise((resolve, reject) => {
      const origin = path.join(from, 'package.json');
      const destination = path.join(to, 'package.json');
      let data = JSON.parse(fs.readFileSync(origin, 'utf-8'));
      delete data.engines;
      delete data.scripts;
      delete data.devDependencies;
      fs.writeFileSync(destination, JSON.stringify(data, null, 2));
      resolve();
    });
  }
docs: Copy and update package.json file.