input val()与span text()比较，如果相等进行操作。

html:

<ul class="tree">
    <li><span class="tree-primary-items open">一级菜单</span>
        <ul class="open">
            <li>
                <div class="tree-secondary-items_search">
                    <span class="placeholder">输入三级菜单名称</span>
                    <input type="text" autocomplete="off" />
                    <button><i class="iconfont icon-search"></i></button>
                </div>
            </li>
            <li><span class="tree-secondary-items">二级菜单A</span>
                <ul class="open">
                    <li><span class="tree-third-items active">三级菜单A</span></li>
                    <li><span class="tree-third-items">三级菜单B</span></li>
                    <li><span class="tree-third-items">三级菜单C</span></li>
                </ul>
            </li>
            <li><span class="tree-secondary-items">二级菜单B</span>
                <ul>
                    <li><span class="tree-third-items">三级菜单D</span></li>
                    <li><span class="tree-third-items">三级菜单E</span></li>
                    <li><span class="tree-third-items">三级菜单F</span></li>
                </ul>
            </li>
        </ul>
    </li>
</ul>

点击搜索按钮，比较inputVal是否等于某个三级菜单名称，如果相等，这个三级菜单添加active，三级菜单的父元素ul添加open。

---

$('span.tree-third-items').each(function(){
    if(inputVal === $(this).text()){
        $(this).addClass('active')
        .parent('li').parent('ul').addClass('open');
    }
})