JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li class="par_cat"></li>
<li class="sub_cat">sub cat</li>
<li class="sub_cat">sub cat</li>
<li class="par_cat">par cat - The element we want</li> 
<li class="sub_cat">sub cat</li>
<li class="sub_cat">sub cat - Immediate previous, the only element the jquery checks </li>
<li class="sub_cat current_sub"> current sub - starting point</li> // this is where I need to start searching
<li class="par_cat"></li>
<li class="sub_cat"></li>
<li class="par_cat"></li>

</ul>

JavaScript

// show blue if it matches the element we want
$('li.current_sub').prev('.par_cat').css({'border':'1px solid #000','background':'#aaf'});

// Show red if it only matches the preceding element
$('li.current_sub').prev('.sub_cat').css({'border':'1px solid #faa','background':'#faa'});