https://www.codecogs.com/assets/js/contact.js

1// Contact form — the one bit of behaviour specific to this page (submit-
2// button gating lives in recaptcha.js, the word-count in
3// contact-word-count.js — both shared with other forms). Vanilla JS,
4// event delegation, no framework — consistent with every other
5// page-specific script in this project.
6(function () {
7  function updateDialCode() {
8    var select = document.querySelector('[data-contact-country]');
9    var out = document.querySelector('[data-contact-dial-code]');
10    if (!select || !out) return;
11    var option = select.options[select.selectedIndex];
12    var dial = option ? option.getAttribute('data-dial') : '';
13    out.textContent = dial || '';
14  }
15
16  document.addEventListener('DOMContentLoaded', updateDialCode);
17  document.addEventListener('change', function (e) {
18    if (e.target.closest('[data-contact-country]')) updateDialCode();
19  });
20})();