/**
 * Call this function when a user clicks on a promotion. This function uses the eventCallBack
 * datalayer variable to handle navigation after the ecommerce data is sent to Google Analytics.
 *
 * @param {Object} promoObj An object representing an internal site promotion.
 */
function onBannerClick(promoName) {
  var promoName = promoName;
  dataLayer.push({ ecommerce: null });  // Clear the previous ecommerce object.
  dataLayer.push({
    'event': 'promotionClick',
    'ecommerce': {
      'promoClick': {
        'promotions': [
         {
           'name': promoName
         }]
      }
    }
  });
}