引入multilevelpushmenu插件

<link rel="stylesheet" href="jquery.multilevelpushmenu.css">
<script type="jquery.min.js"></script>
<script src="jquery.multilevelpushmenu.min.js"></script>

三级导航菜单HTML代码

<nav>
    <h2><i class="fa fa-reorder"></i>所有分类</h2>
    <ul>
        <li>
            <a href="https://jy.tp.yuanmeng.life/"><i class="fa fa-laptop"></i>智慧小屋</a>
            <h2><i class="fa fa-laptop"></i>智慧小屋</h2>
            <ul>
                <li>
                    <a href="https://jy.tp.yuanmeng.life/templates"><i class="fa fa-phone"></i>网站模板</a>
                    <h2><i class="fa fa-phone"></i>网站模板</h2>
                    <ul>
                        <li>
                            <a href="https://jy.tp.yuanmeng.life/templates/5-0-0-0-0-0">企业模板</a>
                        </li>
                        <li>
                            <a href="https://jy.tp.yuanmeng.life/templates/4-0-0-0-0-0">商城模板</a>
                        </li>
                    </ul>
                </li>
                <li>
                    <a href="https://jy.tp.yuanmeng.life/js"><i class="fa fa-desktop"></i>jQuery特效</a>
                    <h2><i class="fa fa-desktop"></i>jQuery特效</h2>
                    <ul>
                        <li>
                            <a href="https://jy.tp.yuanmeng.life/js/7-0-0-0">图片代码</a>
                        </li>
                    </ul>
                </li>
            </ul>
        </li>
    </ul>
</nav>

调用multilevelpushmenu菜单插件

$(function() {
    $('#menu').multilevelpushmenu({
        containersToPush: [$('#pushobj')]
    });
});