performs deep clone. Not able to deep clone closures, enclosed values

DeepClone.js

/*!
 * modified github.com/englishextra/deepclone
 * gist.github.com/englishextra/806a8d0c8a2ca5cceaa2651044331cf1
 * performs deep clone. Not able to deep clone closures, enclosed values
 * still point to original reference, so this is not full deep clone in all situations.
 * Anyway it is able to detect circular references
 */
var DeepClone = function () {
	function clone(x) {
		if (isArray(x)) {
			return cloneArray(x);
		} else if (isFunction(x)) {
			return x;
		} else if (isObject(x)) {
			return cloneObject(x);
		} else {
			return x;
		}
	}
	/**
	 * objects constructed by other functions than Object, because those cannot be
	simply copied as simple object
	 */
	function isObject(o) {
		//typeof o === "object" inclues arrays and everything else, we want to target only objec-objects here
		return Object.prototype.toString.call(o) === "[object Object]";
	};
	function isArray(a) {
		return Object.prototype.toString.call(a) === '[object Array]';
	}
	/**
	 * detects just pure functions
	 */
	function isFunction(f) {
		if (f instanceof Function)
			return true;
		return false;
	}
	function cloneArray(arr) {
		var cloned = arr.map(function (member) {
				return clone(member);
			});
		return cloned;
	}
	/**
	 * @param obj object to clone
	 * @param sources if recursive, allready cloned objects in order to avoid circular references
	 * @param clones allready cloned source objects, for avoiding circular references
	 */
	function cloneObject(obj, sources, clones) {
		if (!obj)
			return obj;
		if (obj.clone && isFunction(obj.clone))
			return obj.clone();
		if (obj instanceof Date) {
			//date is built in type and can be created only by invoking new Date()
			//https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date
			//there are more such objects as Error, but they are ignored here
			return new Date(obj.getTime());
		}
		sources = sources || [];
		clones = clones || [];
		var target = Object.create(obj);
		var properties = Object.getOwnPropertyNames(obj);
		properties.forEach(function (property) {
			var descriptor = Object.getOwnPropertyDescriptor(obj, property);
			descriptor.value = _getValue2Assign(descriptor.value, obj, target, sources, clones);
			Object.defineProperty(target, property, descriptor);
		});
		return target;
	}
	function _getValue2Assign(value, objectBeingCloned, target, sources, clones) {
		if (!isObject(value)) {
			return clone(value);
		} else if (value.clone) { //cloneable
			var target = value.clone();
			if (target && value.constructor.prototype.isPrototypeOf(clone.constructor.prototype)) {
				return target;
			}
			return _getObjectValue2Assign(value, objectBeingCloned, target, sources, clones);
		}
		//else we deal with new object
		return _getObjectValue2Assign(value, objectBeingCloned, target, sources, clones);
	}
	function _getObjectValue2Assign(value, objectBeingCloned, target, sources, clones) {
		var allreadyClonedIndex = sources.indexOf(value);
		if (allreadyClonedIndex !== -1) {
			return clones[allreadyClonedIndex];
		} else {
			sources.push(objectBeingCloned);
			clones.push(target);
			return cloneObject(value, sources, clones);
		}
	}
	/* return {
	clone: clone
	}; */
	return clone;
}
();
var n = DeepClone(x);