实现输入框与下拉框联动效果

<tr>
 <th scope="row">奖励类型：</th>
 <td><input value="" type="text" name="item" id="reward" style="width: 60px;height: 20px;" placeholder="输入关键字" />
 <select name="reward_id" id="reward_id"> 
 <option value="">---请选择---</option>
 {foreach $reward as $value}
 <option value="{$value['material_id']}">{$value['material_name']}</option>
 {/foreach}
 </select>
 </td>
</tr>

<script type="text/javascript">
 $('#reward').bind('input propertychange', function() {reward();});
 function reward()
 {
 var search = $("#reward").val();
 $.ajax({ 
 type:"get", 
 url:"/mall/config_commodity_info/search_commodity_info", 
 data:{search:search}, 
 success:function(select){ 
 var reward_id = $("#reward_id"); 
 if (select) {
 $("option",reward_id).remove();
 var obj = JSON.parse(select);
 for (var key in obj) {
 var option = "<option value='"+key+"'>"+obj[key]+"</option>"; 
 reward_id.append(option); 
 }
 } 
 } 
 });
 } 
</script>

public function add_alms()
{
 $reward = $this->materials->selReward();
 $this->assign('reward',$reward);
 return $this->fetch();
}
public function do_add_alms()
{
 $data = Request::instance()->param();
 $this->alms->addAlms($data);
}