js代码：
function search_area(id){
var url='__URL__/search_area/id'+id;
ThinkAjax.send('__URL__/search_area','ajax=1&id='+id,display_area());
}
function display_area(data,status) {
alert(data);
if (status==1)
{
alert(data);

}
}
</script>
HTML代码：
<select name='parent_area' id='parent_area' onchange="search_area(this.value)" style='width:160px'>
<option value="">--区域--</option>
<foreach name="parent_area" item="p">
<option value="<?php echo $p['id']?>" <if condition="$row['_parent_area']=$p['_name']"> "selected";</if>><?php echo $p['_name'];?></option>
</foreach>
</select>

php代码：
function search_area(){
$id = $_GET['id'];
if(!empty($id)){
$data = M('room_area')->where("parent_id='".$id."'")->select();
$this->ajaxReturn($data, '', 1);
}
alert(data)弹出的信息是undefined；求指点