make non enumerable

x.js

function makeNonEnumerable(obj /*, props */) {
  var names = [].slice.call(arguments, 1);
  names.forEach(makeNonEnumerable);

  function makeNonEnumerable(name) {
    var pd = Object.getOwnPropertyDescriptor(obj, name);
    pd.enumerable = false;
    Object.defineProperty(obj, name, pd);
  }
}