Check Uncheck all CheckBoxes in an ASP.NET GridView using jQuery

<script type="text/javascript">
    $(document).ready(function() {
        var chkBox = $("input[id$='ChkAll']");
        chkBox.click(
             function() {
                 $("#GridView1 INPUT[type='checkbox']")
                 .attr('checked', chkBox
                 .is(':checked'));
             });

        // To deselect CheckAll when a GridView CheckBox
        // is unchecked
        $("#GridView1 INPUT[type='checkbox']").click(
        function(e) {
            if (!$(this)[0].checked) {
                chkBox.attr("checked", false);
            }
        });
    });
</script>