JSFiddle - React, Tailwind, and code Playground

by Reigel Gallarde

HTML

<div class="block-wrap">
    <a href="#">A</a>
    <a href="#">A</a>
    <a href="#">A</a>
    <a href="#">A</a>
    <a href="#">A</a>
</div>

<div class="block-wrap">
    <a href="#">A</a>
    <a href="#">A</a>
    <a href="#">A</a>
    <a href="#">A</a>
    <a href="#">A</a>
    <a href="#">A</a>
</div>

JavaScript

$('div.block-wrap a').each(function() {
    var index = $(this).siblings('a').andSelf().index(this);
    if ((index + 1) % 3 == 0) {
        $(this).after("<span>s</span>");
    }
});