Simple left-to-right mixin

gistfile1.js

var mixin = function () {
  var args = Array.prototype.slice.call(arguments);
  var target = args.shift();
  var source = args.shift();
  // We don't need no hasOwnProperty checks!
  for (var prop in source) {
    target[prop] = source[prop];
  }
  if (args.length) {
    args.unshift(target);
    return mixin.apply(null, args);
  }
  else {
    return target;
  }
};