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Understitial integration

An understitial ad is an interstitial ad which shows up during scroll action underneath the content.

Understitial structure

The understitial ad is a special ad format. Please check the limitations & restrictions section below.

To add an understitial to your webpage it takes only a few lines of code.

  • First, you implement the WebSDK via adding the CDN into the <heady> tag.
<!DOCTYPE html>
      <script src=""></script>

Adding the WebSDK.class.js file

The link to the js file has to be implemented as CDN. Never download the WebSDK or other components from the WebSDK to your servers.

  • Create a new ADvantage instance and pass your license key, siteId and position.
var parallax = new ADvantage_WebSDK('understitialPosition')
                  .setLicenseKey( '[ADvantage License]' )
  • Set the width to 100% and height to 0.
.setWidth( '100%' )
.setHeight( '0px' )
  • Set setTransparent to true
.setTransparent( true )
  • Set the values for setPublisherMaxSize (width, height)
//since ADvantage WebSDK 2.5.3 this function is needed for scaling understitials
  • Besides the generic EventHandlers, you have to add the ADvantageParallaxEvent and select your understitial container to change the position.
  switch (ev.status) {
    case "ADvantageNoCampaignEvent":
      // adserver didn't deliver a campaign
      // in this case you can use a backfill service e.g. Google adsense, etc.
      this.hide(); // hide the ADvantage ad space
      //do something
    case "ADvantageUpdateLayoutEvent":
      //creative is using update layout for the current instance
      //do something
    case "ADvantageAdvertisementEvent":
      //an ADvantage advertisement is loaded; // show the advertisement
      //do something
    case "ADvantageCloseEvent":
      // advertisement closed
      //do something
    case "ADvantageParallaxEvent":'#ADvantage_parallaxContainer')[0].style.cssText="top:50px !important"; // adapt the 50px to your needs
  • Load and display your ad via the initialize() method.
//Request ad

Limitations and restrictions for the understitial

  • As understitial ads are a special ad format, you have to modify your website to correctly display the ad. So before you use it, please contact us first. This special ad format must be tested on your web page to make sure you are able to use it.
  • The understitial ad is working perfectly on iOS with Safari and on Android with Google Chrome. On other browsers there might be some problems. We recommend that you disable this feature or exclude it from bookings for the understitial ad on other browsers. The reason is that other browsers are not supporting the necessary HTML5 functions or they are not correctly working (e.g. graphical glitches).
  • If you use translateZ or translate3d on your website, it could cause problems with the understitial.


The best place to do all this is in the window.onload = function() located in your<body> after your website has been rendered.