function Constructor () {
  // do something with variable args.
  for (var i in arguments) {
    this[i] = arguments[i]
  }
}

function factory () {
  var n = Object.create(Constructor.prototype)
    , o = Constructor.apply(n, arguments)
  return (typeof o === "object" && o) || n
}

var f = factory(1, 2, 3, 4, 5)