https://rpmpower.com/wp-content/plugins/preorders-for-woocommerce-pro/media/js/date-picker.js?ver=2.1.0

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
12    // Datepicker for variation forms loaded using AJAX
13     $('#variable_product_options').delegate('.wc-metabox','click',
14         function() {
15            $('.datepicker').datepicker({
16                'dateFormat': 'yy-mm-dd',
17                'minDate': new Date()
18            });
19        }
20     );
21    var minpreoderDate = $('#preorder_date').data('pre_order_date');
22     // Datepicker for checkout form
23     $('#preorder_date').datepicker({
24        'dateFormat': 'yy-mm-dd',
25         'minDate': minpreoderDate,
26     });
27  
28});