knockout dependencyObservers with notification

See https://groups.google.com/forum/#!topic/knockoutjs/bX8ze5S1w8o

HTML

<script src="https://github.com/downloads/SteveSanderson/knockout/knockout-1.2.1.js"></script>
<html>
    <body>
     Demonstrates using internal observable in a dependentObservable to tigger notifications on write. See <a target="_blank" href="https://groups.google.com/forum/#!topic/knockoutjs/bX8ze5S1w8o">discussion</a>.
         <hr />
        Dependent Observable on testValue 1 <input type="text" data-bind="value: testDependantObservable" \>
        <br/>
        Dependent Observable on testValue 2 <input type="text" data-bind="value: testDependantObservable" \>
    </body>
</html>

JavaScript

sad$(document).ready(function () {
    var testValue = 2;
    var viewModel = {
        testDependantObservable: function() {
            var triggerObservable = ko.observable();
            return ko.dependentObservable({
                // Stub observable to trigger notifications since KO DOs don't notify on write
                triggerObservable: ko.observable(),
                read: function() {
                    this.triggerObservable(testValue);
                    return this.triggerObservable();
                },
                write: function (value) {
                    testValue = value;
                    this.triggerObservable(value);
                }
            })
        }()
    };
    ko.applyBindings(viewModel);
});