只更改可见的父级

Question

我有以下过于复杂的遗留代码，我必须修复。我的问题是在minus_sign / plus_sign切换的两个实例下使用jQuery代码片段。如果显示sub_items，我想要的只是改变的那个：block。如果有人可以帮助我，我会非常感激。希望这是有道理的。

HTML

<li data-id="02" class="nav__module nav__chapter-02">
    <div class="nav__module-heading" role="heading" aria-level="2">
        <a id="headLnk_02" class="trigger_02 chapter_link" href="../content/m01/m01_c02_p00.html">
            <span class="nav__module-heading-number">Module 2</span>
            <span class="nav__module-heading-title menu_ch02">Dashboards</span>
        </a>
        <a tabindex="-1" aria-hidden="true" class="expand_collapse" href="#">
            <span class="fa fa-chevron-down"></span>
            <span class="chapter_expand">Expand</span>
        </a>
    </div>    
    <ul aria-labelledby="headLnk_02" class="nav__items">
        <li class="sub_p01">            
            <span aria-hidden="true">
            <span class="exp plus_sign plus01"><span class="offThePage">plus/minus</span></span>
            <span class="exp minus_sign minus01"><span class="offThePage">plus/minus</span></span>
            </span>

            <a id="subLnk_01" class="parent_link menu_p01" href="../content/m01/m01_c02_p01.html">Publishing dashboard</a>

            <ul aria-labelledby="subLnk_01" class="sub_items">
                <li><a href="../content/m01/m01_c02_p01-a.html" class="menu_p01a" >Publishing process</a></li>
                <li><a href="../content/m01/m01_c02_p01-b.html" class="menu_p01b" >When to use the<br/>Publishing dashboard</a></li>
                <li><a href="../content/m01/m01_c02_p01-c.html" class="menu_p01c" > Approving multiple items</a></li>
            </ul>
        </li>
        <li class="sub_p04">            
            <span aria-hidden="true">
            <span class="exp plus_sign plus04"><span class="offThePage">plus/minus</span></span>
            <span class="exp minus_sign minus04"><span class="offThePage">plus/minus</span></span>
            </span>
            <a id="subLnk_04" class="parent_link menu_p04" href="../content/m01/m01_c02_p04.html">Control panel</a>
            <ul aria-labelledby="subLnk_04" class="sub_items">
                <li><a href="../content/m01/m01_c02_p04-a.html" class="menu_p04a">Site configuration</a></li>
            </ul>
        </li>
    </ul>
</li>  

的jQuery

$( ".sub_items:hidden").attr( "aria-hidden", "true" );
$( ".sub_items:visible").attr( "aria-hidden", "false" );

if($('.sub_items').is(':visible'))
{
    $('.minus_sign').show();
    $('.plus_sign').hide();
}