选择框联查 选择1后再选2再选3

<td align="right">所属镇办：</td>

<!--  onvaluechanged="onDeptChanged"  加载此方法-->

<input id="bumen10" class="mini-combobox"name="TOWN_ID" emptyText="所属镇办" style="150px;" onvaluechanged="onDeptChanged"
           url="${ctx}/aUTHDEPARTMENT/getTownNode" textField="NAME" valueField="ID"showNullItem="true"/>
</td>
<td align="right">所属社区：</td>
<td>
    <input id="bumen20" class="mini-combobox" name="AREA_ID" emptyText="所属社区"onvaluechanged="onDeptChanged1"style="150px;"
           textField="NAME" valueField="ID" shownullitem="true"/>
</td>
<td width="90"align="right" >所属网格：</td>
<td width="90">
    <input id="bumen30" class="mini-combobox" name="GRID_ID" emptyText="所属网格"style="150px;" textField="NAME" valueField="ID" />
</td>

<script type="text/javascript">
    var bumen1 = mini.get("bumen10");
var bumen2 = mini.get("bumen20");
var bumen3 = mini.get("bumen30");
function onDeptChanged(e) {
    var id = bumen1.getValue();
        bumen2.setValue("");
        bumen3.setValue("");
        var url = "${ctx}/aUTHDEPARTMENT/getAreaNode?town_id=" + id
        bumen2.setUrl(url);
        bumen2.select(0);
    }
    function onDeptChanged1(e){
        var id = bumen2.getValue();
        bumen3.setValue("");
        var url = "${ctx}/aUTHDEPARTMENT/getGridNode?area_id=" + id
        bumen3.setUrl(url);
        bumen3.select(0);
    }
</script>