ajax返回二维数组处理++局部数据刷新

<div class="rank">
    <div class="title">排行榜</div>
    <table id="fresh">
        <tr>
            <th>节目名称</th>
            <th>表演部门</th>
            <th>获得票数</th>
        </tr>
        <{foreach from=$rank item=r}>
            <tr add='true'>
                <td><{$r.program_name}></td>
                <td><{$r.department}></td>
                <td><{$r.votes}></td>
            </tr>
        <{/foreach}>
    </table>
</div>

<script type="text/javascript">
$(function(){
	var timer=null;
	timer=setInterval(function(){
		var content='';
		$.ajax({
			type: 'POST',
			url: '?program-rankAjax.html',
			dataType: 'json',
			success:function(json){
				// 二维数组处理
				/*$('#fresh').find('tr[add]').remove();
				for (var i = 0; i < json.length; i++) {//each
					content+='<tr  add="true"><td>'+json[i].program_name+'</td><td>'+json[i].department+'</td><td>'+json[i].votes+'</td></tr>';
				}
				$("#fresh").append(content);*/
				$('#fresh').find('tr[add]').remove();
				$.each(json,function(k,v){
					content+='<tr  add="true"><td>'+v.program_name+'</td><td>'+v.department+'</td><td>'+v.votes+'</td></tr>';
				});
				$("#fresh").append(content);
			}
		});
	},6000);
})
</script>