Real, deep copied objects.

clone.js

function hasOwnProperty(key) {
  if(this[key]) {
    var proto = this.prototype;
    if(proto) {
      return ((key in this.prototype) && (this[key] === this.prototype[key]));
    }
    return true;
  } else {
    return false;
  }
}
if(!Object.prototype.hasOwnProperty) { Object.prototype.hasOwnProperty = hasOwnProperty; }

function create(o) {
  if (arguments.length > 1) {
    throw new Error('Object.create implementation only accepts the first parameter.');
  }
  function F() {}
  F.prototype = o;
  return new F();
}
if(!Object.create) { Object.create = create; }

function isArray( obj ) {
  return Object.prototype.toString.call(obj) === '[object Array]';
}
if(!Array.isArray) { Array.isArray = isArray; }

function clone( obj ) {

  if ( Array.isArray( obj ) ) {
    return [].slice.call( obj, 0 );
  }

  // Create a new object whose prototype is a new, empty object,
  // Using the second propertiesObject argument to copy the source properties
  return Object.create({}, (function(src) {

    var props = Object.getOwnPropertyNames( src ),
      dest = {};

    props.forEach(function( name ) {

      var descriptor = Object.getOwnPropertyDescriptor( src, name ),
        tmp;

      // Recurse on properties whose value is an object or array
      if ( typeof src[ name ] === "object" ) {

        descriptor.value = clone( src[ name ] );
      }

      dest[ name ] = descriptor;

    });

    return dest;

  })( obj ));
}