JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li class="active" style="background-color: hsl(108, 60%, 50%)">One</li>
    <li style="background-color: hsl(36, 60%, 50%)">Two</li>
    <li style="background-color: hsl(252, 60%, 50%)">Three<li>
</ul>

CSS

ul li {
    width: 300px;
    height: 30px;
    border: 1px dashed;
    position: relative;
}

li.active::after {
    content: " 0020";
    display: block;
    font-size: 0px;
    position: absolute;
    left:100%;
    top: 0%;
    width: 0px;
    height: 0px;
    background: transparent;
    border: 17px solid transparent;
    border-left-color: #FF3900;
}

JavaScript

$("ul li").click(function() {
    $("ul li").removeClass("active");
    $(this).addClass("active");
//    $(li.active::after).css('border-left-color', $(this).css('background-color'));
});