transforms.js

const { Transform } = require('stream'); // stream is core Node.js module
const path = require('path')

function _capitalize(name) {
  return name.substring(0, 1).toUpperCase() + name.substring(1)
}



exports.append = function (properties, features) {


  const standalone = features.indexOf('standalone') > -1;

  const extensionName = properties.name
  const unscopedExtensionName = extensionName[0] === '@' ?
    extensionName.substring(extensionName.indexOf('/') + 1) :
    extensionName;
  const extensionPath = path.normalize(unscopedExtensionName).replace('/', '-');
  const extensionPrefix = extensionPath.split('-').map(name => _capitalize(name)).join('');

  properties.extensionPath = extensionPath
  properties.extensionPrefix = extensionPrefix


  return new Transform({
    objectMode: true,
    transform: function (file, env, cb) {

      if (file.isBuffer()) {
        // we don't want another nested folder when 'standalone'
        if (standalone) {
          file.path = file.path.replace("_extensionPath_" + path.sep, "");
        }
        // replace _extensionPath_ in file's path with the calculated name
        file.path = file.path.replace(/_extensionPath_/g, `${extensionPath}`)
      }
      cb(null, file);
    }
  });
};