https://schorgen.ch/wp-content/plugins/pre-orders-for-woocommerce/media/js/date-picker.js?ver=1.2.13

1jQuery(document).ready(function ($) {
2
3    /*
4     * Initialize datepicker
5     */
6    $('.datepicker').datepicker({
7        'dateFormat': 'yy-mm-dd',
8        'minDate': new Date()
9    });
10
11    // Datepicker for variation forms loaded using AJAX
12    $('#variable_product_options').delegate('.wc-metabox', 'click',
13        function () {
14            $('.datepicker').datepicker({
15                'dateFormat': 'yy-mm-dd',
16                'minDate': new Date()
17            });
18        }
19    );
20
21    // Datepicker for checkout form
22    $('#preorder_date').datepicker({
23        'dateFormat': 'yy-mm-dd',
24        'minDate': $('#preorder_date').data('pre_order_date')
25    });
26});