JSFiddle - React, Tailwind, and code Playground
by lbstr
HTML
<div>
<span class="x a">1</span>
<span class="comma">,</span>
<span class="x b">2</span>
<span class="comma">,</span>
<span class="x b">3</span>
<span class="comma">,</span>
<span class="x a">4</span>
<span class="comma">,</span>
<span class="x b">5</span>
<span class="comma">,</span>
<span class="x a">6</span>
<span class="comma">,</span>
<span class="x b">7</span>
<span class="comma">,</span>
<span class="x b">8</span>
<span class="comma">,</span>
<span class="x a">9</span>
<span class="comma">,</span>
</div>
CSS
.a { display: none; }
.red { color: red; }
JavaScript
var $nums = $('.x:visible:not(:last)');
$nums.addClass('red');
$('.comma').hide();
$nums.next('.comma').show();