Creating a smart, dirty flag

http://www.knockmeout.net/2011/05/creating-smart-dirty-flag-in-knockoutjs.html

by WizKid81

HTML

<script src="http://knockoutjs.com/downloads/knockout-2.2.0.js"></script>
<ul data-bind="foreach: items">
    <li data-bind="css: { dirty: dirtyFlag.isDirty }">
        <span data-bind="text: id"></span>
        <input data-bind="value: name" />
        <button data-bind="click: dirtyFlag.reset">Reset</button>
    </li>
</ul>

<button data-bind="enable: isDirty, click: save">Save</button>
<hr />
<h3>Just Dirty Items</h3>
<div data-bind="text: ko.toJSON(dirtyItems)"></div>

CSS

li { padding: 2px; margin: 2px; }
input { width: 75px; }
.dirty { border: solid yellow 2px; }

JavaScript

//////////////////
        ko.subscribable.fn.trackDirtyArrayFlag = function () {
            var original = this();

            this.isDirty = ko.computed(function () {
                console.log("Checking if an array is dirty.");
                console.log(this().length)
                //If there are a different number of elements 
                return false;
            }, this);

            this.revert = function () {
                this(original);
                //return;
            };

            this.update = function () {
                original = this();
                //return;
            }
            
            this.startingValue = function () {
                console.log("startingValue");
            };

            return this;
        };
        /////////////////////////////////
        var hierarchyNode = function (data, parent) {
            var self = this;

            getObservableArray = function (childNodes) {
                var returnArray = ko.observableArray().trackDirtyArrayFlag();

                $(childNodes).each(function (index, element) {
                    var hierarchyItem = new hierarchyNode(element, self);
                    returnArray.push(hierarchyItem);
                })

                return returnArray;
            }

            this.id_field = (data === null || data === undefined || typeof data.ID_Field === "undefined") ? undefined : data.ID_Field;
            this.parent_id = (data === null || data === undefined || typeof data.Parent_ID === "undefined") ? undefined : data.Parent_ID;
            this.name = (data === null || data === undefined || typeof data.Name === "undefined") ? undefined : ko.observable(data.Name).trackDirtyFlag();
            this.hasChildren = (data === null || data === undefined || typeof data.HasChildren === "undefined") ? ko.observable(false) : data.HasChildren == 1 ? ko.observable(true) : ko.observable(false);
            this.childNodes = (data === null || data ===...