Setting the value of Datepicker from a hidden field

Setting the value of Datepicker from a hidden field

I have a page that has a repeating form each of which shows a date (via datepicker).  In the same form is a hidden field which should serve as the minDate for the datepicker.

Try as I might, I can't figure out how to get the value of the hidden sibling into the minDate. I'm pretty sure the problem I'm having is from not properly selecting the hidden field.

If I set the minDate literally to "04/28/2015" ("minDate:04/28/2015") it works as expected.  But, if I use the code below, though the control shows up, the mindate does not seem to be set.

Here is the content of the form: 


<form style="margin:0";>
<input type="hidden" name="StylePatternColor" class="StylePatternColor" value="Bel Air" />
<input type="hidden" class="PromiseDate" name="PromiseDate" value="04/26/2015" />
<input class="date" name="ShipDate" id="ShipDate0" value="04/28/2015" />
<input type="hidden" name="Key" value="0" />
</form>

Can somebody please point me in the right direction?

jQuery(function($) {
$(".date").datepicker({

minDate: $(this).siblings('.PromiseDate').val(),
onSelect: function(dateText) {

var $form = $(this).closest('form'); // get the form element this button belongs to
var theData = $form.serialize(); // generates the data string
// alert(theData);
var newVal = "Dummy";

$.ajax({

type: "GET",

url: "cartDateUp.php?newvalue=" + newVal + "&" + theData,

success: function(data,status){

//$button.parent().find("input").val(newVal);

}

});

}

})

  

});