Bugs of Is( ) in jquery 1.3 , it can't work well,always return True

Bugs of Is( ) in jquery 1.3 , it can't work well,always return True


I want to make such effect as
when click even table row,it's background will turn green.
when click odd table row,it's background will turn red.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script>
$(document).ready(function(){
$(".stripe tr").click(
function(){
if($(this).is(".stripe tr:even"))
$(this).css("background","green");
else
$(this).css("background","red");});
});
</script>
</head>
<body>
<table class="stripe" width="50%" border="0" cellspacing="0"
cellpadding="0">
<thead>
<tr>
<th>name</th>
<th>age</th>
<th>QQ</th>
<th>Email</th>
</tr>
</thead>
<tbody>
<tr>
<td><a href="http://www.google.cn" >goolge</a></td>
<td>cssrain</td>
<td>demo</td>
<td>toggleClass</td>
</tr>
<tr>
<td>demo</td>
<td>23</td>
<td>31540205</td>
<td>gl.deng@gmail.com</td>
</tr>
<tr>
<td>demo</td>
<td>23</td>
<td>31540205</td>
<td>gl.deng@gmail.com</td>
</tr>
</tbody>
</table>
</body>
</html>