magemail-promo-bar-custom-js.html

<script>
  MageMailData = typeof(MageMailData) != 'undefined' ? MageMailData : {};
  MageMailData.beforeInit = function() {
      var cookies = new MageMail_Cookies();
      var coupon = cookies.get('mm_coupon');
      if (!coupon || coupon == '') {
          MageMail_Magento.applyCouponToCart('BLACK_FRIDAY_10_OFF', 'custom_javascript');
          cookies.set('mm_countdown', '2015-11-07T04:00:00+00:00'); // UTC
          MageMail_Magento.setupCountdownTimer();
      }
  };
</script>