多级菜单结构图

<ul id="ddsubmenu1" class="ddsubmenustyle">
    <li><a href="https://jy.tp.yuanmeng.life/">Item 1a</a></li>
    <li><a href="https://jy.tp.yuanmeng.life/">Item 2a</a></li>
    <li>
        <a href="https://jy.tp.yuanmeng.life/">Item Folder 3a</a>
        <ul>
            <li><a href="https://jy.tp.yuanmeng.life/">Sub Item 3.1a</a></li>
            <li><a href="https://jy.tp.yuanmeng.life/">Sub Item 3.2a</a></li>
            <li><a href="https://jy.tp.yuanmeng.life/">Sub Item 3.3a</a></li>
            <li><a href="https://jy.tp.yuanmeng.life/">Sub Item 3.4a</a></li>
        </ul>
    </li>
    <li><a href="https://jy.tp.yuanmeng.life/">Item 4a</a></li>
    <li>
        <a href="https://jy.tp.yuanmeng.life/">Item Folder 5a</a>
        <ul>
            <li><a href="https://jy.tp.yuanmeng.life/">Sub Item 5.1a</a></li>
            <li>
                <a href="https://jy.tp.yuanmeng.life/">Item Folder 5.2a</a>
                <ul>
                    <li><a href="https://jy.tp.yuanmeng.life/">Sub Item 5.2.1a</a></li>
                    <li><a href="https://jy.tp.yuanmeng.life/">Sub Item 5.2.2a</a></li>
                    <li><a href="https://jy.tp.yuanmeng.life/">Sub Item 5.2.3a</a></li>
                    <li><a href="https://jy.tp.yuanmeng.life/">Sub Item 5.2.4a</a></li>
                </ul>
            </li>
        </ul>
    </li>
    <li><a href="https://jy.tp.yuanmeng.life/">Item 6a</a></li>
</ul>

引入并调用无限菜单插件ddlevelsmenu.js

<script type="text/javascript" src="js/ddlevelsmenu.js"></script>

//顶部菜单栏示例
ddlevelsmenu.setup("ddtopmenubar", "topbar")
//侧面菜单栏示例
ddlevelsmenu.setup("ddsidemenubar", "sidebar")