用jquery 获取一个表格里面第3行第4列的值

<script type="text/javascript" src="http://www.w3school.com.cn/jquery/jquery.js"></script>
<script type="text/javascript"> 

$(document).ready(function(){

 var tt =  $("tr:eq(2)>td:eq(3)").css("background-color","red").text();
 alert(tt);
});

</script>