This documentation is for developers that want to implement their own
callback to react on the invisible recaptcha.


=== Required: hook_recaptcha_callback_alter($callback, $captcha) ===

The hook_recaptcha_callback_alter() hook is the only required function if you want to alter
the implementation of the invisible recaptcha callback function.
First of all define the name of your javascript fallback function:
  * 'callback': return a string
  * 'captcha': this is the captcha array from the captcha module's hook_captcha.
               Here you can add your custom javascript file from your module.
               In this javascript file the custom callback function should be defined.

Let's give a simple example to make this more clear.

"""

custom_module.module

/**
 * Implements hook recaptcha_callback
 * @see recaptcha_captcha
 * @param string $callback
 * @param array $captcha
 */
function custom_module_recaptcha_callback_alter(&$callback, &$captcha) {
  $custom_js = array(
    drupal_get_path('module', 'custom_module') . '/js/invisible-recaptcha-custom.js',
  );
  $captcha['form']['#attached']['js'] = $custom_js;
  $callback = 'onCustomInvisibleSubmit';
}

"""

js/custom_js.js

/*
 * Override invisible-recaptcha.js - onInvisibleSubmit(token) callback function
 * re-use the filled in submittedFormId variable from validateInvisibleCaptcha
 */
function onInvisibleWebformSubmit(token) {
  // retrieve the form where the captcha applied to - stored in var submittedFormId
  // see invisible-recaptcha.js
  var $form = jQuery(document.getElementById(submittedFormId));
  //Check if we're handling a webform
  if($form.attr('id').indexOf('webform-client-form') >= 0) {
    // If we have a webform and a multifile upload, make sure to reset that first
    if($form.has('.webform-component-multifile').length > 0) {
      // Empty Element Fix!!! see jquery.MultiFile.js:45
      // this code will automatically intercept native form submissions and disable empty file elements
      // As we intercepted the form submit and handling it now asynchronously we need to invoke this ourselves
      jQuery.fn.MultiFile.disableEmpty();
    }
  }
  //submit the form
  $form.submit();
}