https://www.urs.cz/js/prevent-double-submit.js?m=1788331671

1document.addEventListener("DOMContentLoaded", function(event) {
2    var forms = document.querySelectorAll("form[data-prevent-dblsubmit]");
3    var i;
4    for (i = 0; i < forms.length; i++) {
5        var form = forms[i];
6        form.addEventListener("submit", function() {
7            this.setAttribute('data-prevent-dblsubmit', 'submitted');
8            var spinner = document.querySelector('form[data-prevent-dblsubmit=submitted] .form-spinner');
9            if (!spinner) {
10                spinner = createSpinner(form);
11            }
12            spinner.style.display = 'block';
13            
14            var buttons = document.querySelectorAll('[data-prevent-dblsubmit] input[type=submit]');
15            var focused = document.querySelector(':focus');
16
17            for (j = 0; j < buttons.length; j++) {
18                buttons[j].setAttribute('disabled', true);
19            }
20            if (focused) {
21                focused.blur();
22            }
23        });
24    }
25});