>age</code>. If we had
not set a default value here, the <code>orderBy</code> filter would remain uninitialized until our
user picked an option from the drop down menu.</p>
<p>This is a good time to talk about two-way data-binding. Notice that when the app is loaded in the
browser, &quot;Newest&quot; is selected in the drop down menu. This is because we set <code>orderProp</code> to <code>&#39;age&#39;</code>
in the controller. So the binding works in the direction from our model to the UI. Now if you
selec