JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
<div>Content</div>
<div>Content</div>
<div>Content</div>
</div>

<a href="#" id="btn">Click</a>

CSS

div {
    margin-bottom: 20px;
}

JavaScript

$('#btn').click(function(e){
    e.preventDefault();
    
    var length = $('#container').children('div').length;
    console.log(length);
    
    $('#container').children('div').clone().attr('id',"pack" + (length )).appendTo($('#container'));
});
var max = 15;
var arr = $('#container').children('div');

$.each(arr, function(i) {
    
    $(this).remove();
    
    if( i == max) {
       return false; 
    }
    counter++;
});