javascript function prototype

foo.js

function foo (p, v) {
  if (arguments.length > 1) {
    arguments.callee[p] = v
  }
  return arguments.callee[p]
}

function arrayFunction (arr) {
  for (var i = 0; i < arr.length; i++) {
    this[i] = arr[i]
  }
}
arrayFunction.prototype = foo

var a = new arrayFunction([1, 3, 4])
  , b = new arrayFunction([1, 3, 4])

a(1)
b(0, -1)

Note that a(1) throws a TypeError of type called_non_callable, while a.__proto__(1) is fine. That does not make sense.

Simpler example here https://gist.github.com/1282497

The issue is that new always returns an object, unless the ctor explicitly returns something else. Try this:

function bar (p) { return p }
function barcons () {
  var f = function () {}
  f.__proto__ = barcons.prototype
  return f
}
barcons.prototype=bar
var c = new barcons
c(1)

Of course, this is evil and stupid, and will probably send the interpreter into some kind of crazy bad place. But you're already using arguments.callee, so clearly you're ok with evil ;)