document.addEventListener('DOMContentLoaded', function() {
  var form = document.querySelector('form'); // или '#form12345'

  if (!form) return;

  form.addEventListener('submit', function(event) {
    event.preventDefault();
    grecaptcha.ready(function() {
      grecaptcha.execute('6LeqxVQrAAAAAKdYGqgvM3nazkX9yPrX5rrsEw0S', {action: 'submit'})
      .then(function(token) {
        var recaptchaInput = form.querySelector('input[name="recaptcha_response"]');
        if (!recaptchaInput) {
          recaptchaInput = document.createElement('input');
          recaptchaInput.type = 'hidden';
          recaptchaInput.name = 'recaptcha_response';
          form.appendChild(recaptchaInput);
        }
        recaptchaInput.value = token;
        form.submit();
      });
    });
  });
});