how to count the rows of gridview in asp net using jquery

1<script type="text/javascript">
2    $(function () {
3        $("[id*=btnGetCount]").click(function () {
4            var totalRowCount = $("[id*=GridView1] tr").length;
5            var rowCount = $("[id*=GridView1] td").closest("tr").length;
6            var message = "Total Row Count: " + totalRowCount;
7            message += "\nRow Count: " + rowCount;
8            alert(message);
9            return false;
10        });
11    });
12</script>