为什么用ajax做遍历不出来div,该如何处理

为什么用ajax做遍历不出来div
这是我的json
[{"wid":"1","con":"\u8fd9\u662f\u4e00\u4e2a\u795d\u798f","addtime":"1338972738","wname":"\u5c0f\u738b"},{"wid":"2","con":"\u8fde\u63a5\u6570\u636e\u5e93","addtime":"1338972764","wname":"\u5c0f\u674e"}]
这是另外一个代码页

HTML code

<script type="text/javascript">            $(function(){                $.ajax({                    type:'post',                    url:'selectsql.php',                    dataType:'json',                    success:function(data){                        var str='';                        for(var i in data){                            alert (data[i]['wid']);                            str+="<div>这是第"+data[i]['wid']+"条留言\                            "+data[i]['con']+"\                            留言时间"+data[i]['addtime']+"署名\                            "+data[i]['wname']+"</div>";                        }                        $('body').append(str);                    }                })            })        </script>