Helper Functions:

Example#1:
On from date selection, to date should be changed and 7 days should be added.

<script type=”text/javascript” language=”javascript”>
jQuery(document).ready(function($){
<?php

$wpdp_options_db = get_option(‘wpdp_options’);
?>

$(“#dt1”).datepicker({
dateFormat: “<?php echo $wpdp_options_db[‘dateFormat’]; ?>”,
minDate: 0,
onSelect: function (date) {
var date2 = $(‘#dt1’).datepicker(‘getDate’);
date2.setDate(date2.getDate()+7);
$(‘#dt2’).datepicker(‘setDate’, date2);
}
});
$(‘#dt2’).datepicker({
dateFormat: “<?php echo $wpdp_options_db[‘dateFormat’]; ?>”
});

});
</script>