deeply remove "private _properties" of JavaScript objects

gistfile1.js

function removePrivateProperties(dirty) {
  return Object.keys(dirty).reduce(function(clean, keyName) {
    if (keyName.indexOf('_') === 0) {
      return clean;
    }

    var value = dirty[keyName];

    if (typeof value === 'object' && Object.keys(value).length > 0) {
      value = removePrivateProperties(value);
    }

    clean[keyName] = value;

    return clean;
  }, {});
}