Open the calendar.
Examples
Open Close
<button class="gj-button-md" onclick="$datepicker.open()">Open</button>
<button class="gj-button-md" onclick="$datepicker.close()">Close</button>
<hr/>
<input id="datepicker" width="312" />
<script>
var $datepicker = $('#datepicker').datepicker();
</script>