Change tracking for flat viewmodels, all properties must be observables

flatchangetracking.js

var getObjProperties = function (obj) {
    var objProperties = [];
    var val = ko.utils.unwrapObservable(obj);

    if (val !== null && typeof val === 'object') {
        for (var i in val) {
            if (val.hasOwnProperty(i)) objProperties.push({ "name": i, "value": val[i] });
        }
    }

    return objProperties;
};

ko.extenders.trackChange = function (target, track) {
    if (track) {
        target.isDirty = ko.observable(false);
        target.originalValue = target();
        target.subscribe(function (newValue) {
            // use != not !== so numbers will equate naturally
            target.hasValueChanged(newValue != target.originalValue);
            target.hasValueChanged.valueHasMutated();
        });
    }

    return target;
};

var applyChangeTrackingToObservable = function (observable) {
    // Only apply to basic writeable observables
    if (observable && !observable.nodeType && !observable.refresh && ko.isObservable(observable)) {
        if (!observable.isDirty) observable.extend({ trackChange: true });
    }
};

var applyChangeTracking = function (obj) {
    var properties = getObjProperties(obj);
    ko.utils.arrayForEach(properties, function (property) {
        applyChangeTrackingToObservable(property.value);
    });
};

var getChangesFromModel = function (obj) {
    var changes = null;
    var properties = getObjProperties(obj);

    ko.utils.arrayForEach(properties, function (property) {
        if (property.value != null && typeof property.value.isDirty != "undefined" && property.value.isDirty()) {
            changes = changes || {};
            changes[property.name] = property.value();
        }
    });

    return changes;
};