let requestSent = false;
const refreshCaptcha = () => {
    if (requestSent) return false;
    requestSent = true;
    fetch('/captcha-regenerate', {headers: {'X-Requested-With': 'XMLHttpRequest'}})
      .then(response => response.text())
      .then(data => document.getElementById('captcha-img')?.setAttribute('src', data))
      .catch()
      .finally(() => requestSent = false);
};