jQuery基于排序功能实现上移、下移的方法

<tr id="{sh:$vo.id}">
 <td>
 <span onclick="up(this);" class="glyphicon glyphicon-arrow-up text-danger up" style="cursor: pointer;" title="上移" aria-hidden="true"></span>
 
 <span onclick="down(this);" class="glyphicon glyphicon-arrow-down text-danger down" style="cursor: pointer;" title="下移" aria-hidden="true"></span>
 </td>
 <td>
 <span title="{sh:$vo.user_id}">{sh:$vo.store_name}</span>
 </td>
 <td class="center"><a href="{sh:$vo.logo}" target="_blank"><img src="{sh:$vo.logo}" width='30px;'></td>
 <td class="center">{sh:$vo.category_name}</td>
 <td class="center edit">
 <a val="{sh:$vo.store_id}" onclick="view(this);" class="view btn btn-success" href="javascript:void(0);" title="查看">
 <i class="halflings-icon white zoom-in"></i>
 </a>
 </td>
</tr>

// 上移
function up(obj){
 var $tr = $(obj).parents("tr");
 if ($tr.index() != 0) {
 var current_id = $tr.attr('id');
 var exchange_id = $tr.prev("tr").attr('id');
 $.ajax({
 url: '{sh::U("Mall/ajax","todo=exchange_sort")}',
 type: 'POST',
 data: 'current_id='+current_id+'&exchange_id='+exchange_id,
 success:function(json) {
 if (json == 1) {
 $tr.fadeOut().fadeIn();
 $tr.prev().before($tr);
 layer.msg('上移成功', {icon: 1});
 } else {
 layer.msg('上移失败', {icon: 2});
 }
 }
 });
 }
}
// 下移
function down(obj) {
 var len = $(".down").length;
 var $tr = $(obj).parents("tr");
 if ($tr.index() != len - 1) {
 var current_id = $tr.attr('id');
 var exchange_id = $tr.next("tr").attr('id');
 $.ajax({
 url: '{sh::U("Mall/ajax","todo=exchange_sort")}',
 type: 'POST',
 data: 'current_id='+current_id+'&exchange_id='+exchange_id,
 success:function(json) {
 if (json == 1) {
 $tr.fadeOut().fadeIn();
 $tr.next().after($tr);
 layer.msg('下移成功', {icon: 1});
 } else {
 layer.msg('下移失败', {icon: 2});
 }
 }
 });
 }
}

case 'exchange_sort':
$mallShopModel = M('Mall_shop');
$current_id = $this->_post('current_id','trim');
$exchange_id = $this->_post('exchange_id','trim');
$current_sort = $mallShopModel->where(array('id'=>$exchange_id))->getField('sort');
$exchange_sort = $mallShopModel->where(array('id'=>$current_id))->getField('sort');
$cdata['id'] = $current_id;
$cdata['sort'] = $current_sort;
$cres = $mallShopModel->save($cdata);
$edata['id'] = $exchange_id;
$edata['sort'] = $exchange_sort;
$eres = $mallShopModel->save($edata);
if ($cres !== FALSE && $eres !== FALSE){
 exit('1');
} else {
 exit('2');
}