JSFiddle - React, Tailwind, and code Playground

HTML

<div>                                       <!-- NOT THIS -->
    <h1>Magical ponies</h1>                 <!-- NOT THIS -->
    <ul>                                    <!-- NOT THIS -->
        <li>Fluttershy</li>                 <!-- NOT THIS -->
        <li>Pinkie pie</li>                 <!-- NOT THIS -->
        <li>Twilight sparkle</li>           <!-- THIS -->
        <li>Hurdurrdurr</li>                <!-- NOT THIS -->
    </ul> 
</div>
<div>Twilight is a movie too <span>Twilight</span></div>          <!-- THIS -->
<p>Hurr durr                                <!-- NOT THIS -->
    <span>Twilight <span>ZONE</span></span>              <!-- THIS -->
Durr</p>

JavaScript

var v = $('*').contents().filter(function(){
    return this.data && this.data.match(/Twilight/g);
}).parent();
v.children().each(function(){
    v = v.has(this)?v.not(this):v;
});
v.css('border-left', '1px solid purple');