JSFiddle - React, Tailwind, and code Playground

by Michaël Vanbrabandt

HTML

<div class="wrapper">
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
</div>
<div class="wrapper">
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
  <div class="item"></div>
</div>

JavaScript

$('.wrapper').each(function() {
    $.each($(this).children('.item'), function(k,v) { // k = index, v = value
        $(this).addClass('div-' + (k < 9 ? '0' : '') + (k+1));
    });
});