Question

I am trying to customize this script so that so that onclick #startdatepicker would show this Sunday’s date in yy-mm-dd format and #enddatepicker would show next sat. date by default.

<script type="text/javascript">
    $(document).ready(function() {
        $("#startdatepicker").datepicker({
            dateFormat: 'yy-mm-dd'
        });
        $("#enddatepicker").datepicker({
            dateFormat: 'yy-mm-dd',
        });
    });
</script>

Start Date: <input type="text" id="startdatepicker"/><br />
End Date: <input type="text" id="enddatepicker"/><br />`

Answer 1

If you always want the datePicker to default to the next Sunday (regardless of today’s date), try:

$(function() {
    var sunday = new Date(),               // new Date object for current day
        dow = sunday.getDay(),             // day of week (0-6)
        toAdd = dow === 0 ? 0 : 7 - dow;   // days to move forward

    $( "#startpicker" ).datepicker({
        dateFormat: 'yy-mm-dd',
        defaultDate: toAdd
    });

    $( '#endpicker' ).datepicker({
        dateFormat: 'yy-mm-dd',
        defaultDate: toAdd+6
    });
});​

The same can be done to find the following Saturday, just add 6 more days.

http://jsfiddle.net/dYEMn/3