# 前端新增代碼 * [ ] `介紹` 由于有些功能尚未開發，在原有基礎上新加的功能，用法詳見模板使用。 ***** ## 二級導航欄目功能，使用場景(如下圖)  在\addons\cms\view\default\common文件夾下新建一個tow_nav.html文件，代碼如下。 ``` <?php $isOnePage = $channel['id'] ?? false ?? true; ?> {if $isOnePage} <ul class="tow_nav"> {cms:channellist id="nav" type="top" } {if $nav.id == $channel['id']} <!-- 表單頁 --> {cms:channellist id="sub2" type="son" typeid="$nav.id" condition="1=isnav"} <li class="tow_nav_item"> <a href="{$sub2.url}" class="towa_nav_link {if $sub2.url == $channel.url} orange{/if}">{$sub2.name}</a> </li> {/cms:channellist} {else /} <!-- 單頁 --> {cms:channellist id="sub" type="son" typeid="$nav.id" condition="1=isnav" condition="1=isnav"} {if $sub.id == $channel['id']} {cms:channellist id="sub2" type="son" typeid="$sub.parent_id" condition="1=isnav"} <li class="tow_nav_item"> <a href="{$sub2.url}" class="towa_nav_link {if $sub2.id == $channel.id} orange{/if}">{$sub2.name}</a> </li> {/cms:channellist} {/if} {/cms:channellist} {/if} {/cms:channellist} </ul> {else/} <?php $__CHANNEL__['parent_id'] == 0 ? $channelId = $__CHANNEL__['id'] : $channelId = $__CHANNEL__['parent_id']; ?> <ul class="tow_nav"> <!-- 列表頁 --> {cms:channellist id="sub" type="son" typeid="$channelId" condition="1=isnav"} <li class="tow_nav_item"> <a href="{$sub.url}" class="towa_nav_link {if $sub.id == $__CHANNEL__.id} orange{/if}">{$sub.name}</a> </li> {/cms:channellist} </ul> {/if} ```