sliding date range

jquery ui datepicker and knockout allow for sliding date range to be set

HTML

<script src="http://ajax.aspnetcdn.com/ajax/knockout/knockout-2.2.1.js"></script>
From
<input type="text" id="StartDate" data-bind="value: myStartDate" />to
<input type="text" id="EndDate"  data-bind="value: myEndDate"/>
<hr/>
<p>start day<span data-bind="text: myStartDate()" />
</p>
<p>end day<span data-bind="text: myEndDate()" />
</p>

JavaScript

var myViewModel = function () {
    var self = this;
    self.myStartDate = ko.observable();
    self.myEndDate = ko.observable();
};
ko.applyBindings(new myViewModel());

//calendar controls
//setup min and max date ranges
var d = new Date();
d.setDate(d.getDate());
//default range
var defRange = 30;
// total range 1yr +/-
var e = new Date();
var xDate = 365;
e.setDate(d.getDate() - xDate);

$('#StartDate').datepicker({
    maxDate: d,
    beforeShow: function () {
        $('.ui-datepicker').css('font-size', 10);
    },
    onSelect: function (date) {
        var dp2 = $('#EndDate');
        var startDate = $(this).datepicker('getDate');
        var minDate = $(this).datepicker('getDate');
        startDate.setDate(startDate.getDate() + xDate);
        //defaults to past 30 days
        dp2.datepicker('setDate', -defRange);
        minDate.setDate(minDate.getDate() - xDate);
        //set max date for start and end range
        dp2.datepicker('option', 'maxDate', startDate);
        dp2.datepicker('option', 'minDate', minDate);
        $(this).datepicker('option', 'minDate', minDate);
    }
});

$('#EndDate').datepicker({
    maxDate: d,
    minDate: e,
    beforeShow: function () {
        $('.ui-datepicker').css('font-size', 10);
    }
});

$('#StartDate').focus(function () {
    $('#StartDate').datepicker('show');
});

$('#EndDate').focus(function () {
    $('#EndDate').datepicker('show');
});