How to properly clone an object/constructor in Javascript without loosing data.

deepextend.js

Object.deepExtend = function(destination, source) {
  for (var property in source) {
    if (source[property] && source[property].constructor && source[property].constructor === Object) {
      destination[property] = destination[property] || {};
      arguments.callee(destination[property], source[property]);
    } else {
      destination[property] = source[property];
    }
  }
  return destination;
};