p>The model must always be a Date object, otherwise Angular will throw an error.
Invalid <code>Date</code> objects (dates whose <code>getTime()</code> is <code>NaN</code>) will be rendered as an empty string.
If the model is not set to the first of the month, the next view to model update will set it
to the first of the month.</p>
<p>The timezone to be used to read/write the <code>Date</code> instance in the model can be defined using
<a href="api/ng/directive/ngModelOptions">ngModelOptions</a>. By default,