JSFiddle - React, Tailwind, and code Playground

by sozonov

HTML

<ul class="list_availability">
    <li>sdf</li>
    <li>sdf</li>
    <li>sdf</li>
    <li>sdf</li>
    <li>sdf</li>
    <li>sdf</li>
    <li>sdf</li>
    <li>sdf</li>
</ul>

CSS

li {
    border: 1px solid blue;   
    width: 30%;
    height: 30px;
    float:left;
    display:relative;
    margin: 2px;
}

.lastRow {
    border: 2px dashed red;
}

JavaScript

var last = $("ul.list_availability li").length % 3;

if (last == 0) 
    last = 3;

$("ul.list_availability li")
    .slice(-last)
    .addClass("lastRow");