How to use jQuery UI Calendar/Date PIcker for week rather than day?

Here is another way at going at it. -Display the week with showWeek. - Define a beforeShow to attach an event handler using live() so the week row is highlighted (including the week number). - Detach the event handler with die() onclose. This is particularly handy when you are using normal datepickers elsewhere in your code.

$( ".week-picker" ).datepicker({
    dateFormat: "yy-mm-dd",
    showOtherMonths: true,
    selectOtherMonths: true,
    changeMonth: true,
    changeYear: true,
    showWeek: true,
    beforeShow: function(dateText, inst) { 

        // for week highighting
        $(".ui-datepicker-calendar tr").live("mousemove", function() { 
            $(this).find("td a").addClass("ui-state-hover"); 
            $(this).find(".ui-datepicker-week-col").addClass("ui-state-hover");
        });
        $(".ui-datepicker-calendar tr").live("mouseleave", function() { 
            $(this).find("td a").removeClass("ui-state-hover");
            $(this).find(".ui-datepicker-week-col").removeClass("ui-state-hover");      
        });
    },
    onClose: function(dateText, inst) { 
        var wk = $.datepicker.iso8601Week(new Date(dateText));
        if (parseInt(wk) < 10) {
            wk = "0" + wk;
        }           
        var year = $("#ui-datepicker-div .ui-datepicker-year :selected").val();

        if (isNaN(wk)) {
            $(this).val("");
        } else {
            $(this).val(year + ";" + wk);
        }

        // disable live listeners so they dont impact other instances
        $(".ui-datepicker-calendar tr").die("mousemove");
        $(".ui-datepicker-calendar tr").die("mouseleave");

    }
});

Inline week picker using jQuery UI DataPicker (requires jQuery UI 1.8+):

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.1/jquery.js"></script>
    <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.14/jquery-ui.min.js"></script>
    <link rel="stylesheet" type="text/css" media="screen" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.14/themes/base/jquery-ui.css">
<script type="text/javascript">
$(function() {
    var startDate;
    var endDate;

    var selectCurrentWeek = function() {
        window.setTimeout(function () {
            $('.week-picker').find('.ui-datepicker-current-day a').addClass('ui-state-active')
        }, 1);
    }

    $('.week-picker').datepicker( {
        showOtherMonths: true,
        selectOtherMonths: true,
        onSelect: function(dateText, inst) { 
            var date = $(this).datepicker('getDate');
            startDate = new Date(date.getFullYear(), date.getMonth(), date.getDate() - date.getDay());
            endDate = new Date(date.getFullYear(), date.getMonth(), date.getDate() - date.getDay() + 6);
            var dateFormat = inst.settings.dateFormat || $.datepicker._defaults.dateFormat;
            $('#startDate').text($.datepicker.formatDate( dateFormat, startDate, inst.settings ));
            $('#endDate').text($.datepicker.formatDate( dateFormat, endDate, inst.settings ));

            selectCurrentWeek();
        },
        beforeShowDay: function(date) {
            var cssClass = '';
            if(date >= startDate && date <= endDate)
                cssClass = 'ui-datepicker-current-day';
            return [true, cssClass];
        },
        onChangeMonthYear: function(year, month, inst) {
            selectCurrentWeek();
        }
    });

    $('.week-picker .ui-datepicker-calendar tr').live('mousemove', function() { $(this).find('td a').addClass('ui-state-hover'); });
    $('.week-picker .ui-datepicker-calendar tr').live('mouseleave', function() { $(this).find('td a').removeClass('ui-state-hover'); });
});
</script>
</head>
<body>
    <div class="week-picker"></div>
    <br /><br />
    <label>Week :</label> <span id="startDate"></span> - <span id="endDate"></span>
</body>
</html>

run it on JsFiddle http://jsfiddle.net/manishma/AVZJh/light/