JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/ui-lightness/jquery-ui.css">
<div class='container'>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
    <div class='item'>item</div>
</div>

CSS

.inner-container {
    border: 2px dashed orange;
}

JavaScript

var items = $(".container .item"),i=0;

while( i < items.length ) {
    items.slice( i,i+=15 ).wrapAll('<div class="inner-container"></div>');
}