ffdn.org/sites/all/modules/captcha/captcha.js

(function ($) {

  Drupal.behaviors.captcha = {
    attach: function (context) {

      // Turn off autocompletion for the CAPTCHA response field.
      // We do it here with JavaScript (instead of directly in the markup)
      // because this autocomplete attribute is not standard and
      // it would break (X)HTML compliance.
      $("#edit-captcha-response").attr("autocomplete", "off");

    }
  };

  Drupal.behaviors.captchaAdmin = {
    attach: function (context) {
      // Add onclick handler to checkbox for adding a CAPTCHA description
      // so that the textfields for the CAPTCHA description are hidden
      // when no description should be added.
      // @todo: div.form-item-captcha-description depends on theming, maybe
      // it's better to add our own wrapper with id (instead of a class).
      $("#edit-captcha-add-captcha-description").click(function() {
        if ($("#edit-captcha-add-captcha-description").is(":checked")) {
          // Show the CAPTCHA description textfield(s).
          $("div.form-item-captcha-description").show('slow');
        }
        else {
          // Hide the CAPTCHA description textfield(s).
          $("div.form-item-captcha-description").hide('slow');
        }
      });
      // Hide the CAPTCHA description textfields if option is disabled on page load.
      if (!$("#edit-captcha-add-captcha-description").is(":checked")) {
        $("div.form-item-captcha-description").hide();
      }
    }

  };

})(jQuery);