aop.js

function after (method, fn) {
  var orig = this[method];
  if (orig === after || fn === after) throw new Error(
    "That's not a good idea. Please don't be dumb."
  );
  this[method] = function aop_after () {
    var ret = orig.apply(this, arguments);
    var newArgs = Array.prototype.slice.call(arguments,0);
    if (ret !== undefined) newArgs.concat(ret);
    var nextRet = fn.apply(this, newArgs);
    return (nextRet !== undefined) ? nextRet : ret;
  };
  for (var i in orig) this[method][i] = orig[i];
  return this;
}

function before (method, fn) {
  var orig = this[method];
  if (orig === before || fn === before) throw new Error(
    "That's not a good idea. Please don't be dumb."
  );
  this[method] = function aop_before () {
    var ret = fn.apply(this, arguments);
    var newArgs = Array.prototype.slice.call(arguments,0);
    if (ret !== undefined) newArgs.concat(ret);
    var nextRet = orig.apply(this, newArgs);
    return (nextRet !== undefined) ? nextRet : ret;
  };
  for (var i in orig) this[method][i] = orig[i];
  return this;
}