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Out-of-page ads

Out-of-page ads are formats that don't live in the normal content flow - interstitials and anchor (sticky) ads. GAM defines them via defineOutOfPageSlot instead of the regular defineSlot used for in-page slots. moli supports GAM's raw formats directly, and also offers hybrid positions that combine a raw GAM format with prebid demand through a waterfall.

The waterfall concept​

A hybrid position (interstitial, anchor-bottom, anchor-top) doesn't pick a single ad source. It runs a waterfall between two channels:

  • gam - the raw GAM out-of-page format (Web Interstitial / Anchor)
  • c ("custom") - a regular in-page slot at the same domId, filled by prebid demand

Which channel is used for the next ad request is decided by a priority list (priority: ['gam', 'c'] or ['c', 'gam']), persisted in storage per domId. The winning channel is kept as long as it keeps delivering; priority only shifts to the next channel once the current one fails (empty GAM ad, or no prebid bid). This lets you e.g. prefer prebid demand but fall back to GAM's native format when nobody bids, without re-auctioning both on every single page view. If priority is empty, the position is not requested at all.

Interstitials shift on every attempt (success or fail) instead - a GAM-hardwired frequency cap on the Web Interstitial format requires giving other channels a turn even after a successful render. Anchor ads have no such cap, so they use the fail-only policy described above.

Supported formats​

out-of-page​

The generic GAM out-of-page format (e.g. a native ad that doesn't fit a standard size). No waterfall - always requested through GAM.

const slot: Moli.AdSlot = {
  domId: 'content_native',
  adUnitPath: '/1234/content_native',
  sizes: [[1, 1]],
  position: 'out-of-page',
  behaviour: { loaded: 'eager' },
  sizeConfig: []
};

out-of-page-interstitial​

Raw GAM Web Interstitial. No prebid demand, no waterfall - use the interstitial position below if you want prebid to compete.

const slot: Moli.AdSlot = {
  domId: 'interstitial_gam_only',
  adUnitPath: '/1234/interstitial',
  sizes: [[1, 1]],
  position: 'out-of-page-interstitial',
  behaviour: { loaded: 'eager' },
  sizeConfig: []
};

out-of-page-top-anchor / out-of-page-bottom-anchor​

Raw GAM anchor (sticky) ad, pinned to the top or bottom of the viewport by GAM itself. Collapsibility is a GAM line-item/creative setting, not something configured here. No prebid demand, no waterfall.

const slot: Moli.AdSlot = {
  domId: 'floorad',
  adUnitPath: '/1234/floorad',
  sizes: [[320, 50]],
  // swap for 'out-of-page-top-anchor' to pin to the top instead
  position: 'out-of-page-bottom-anchor',
  behaviour: { loaded: 'eager' },
  sizeConfig: []
};

See Traffic anchor ads on web and Collapsible anchor ads for web for more information.

interstitial​

Hybrid: waterfall between a custom (prebid) interstitial and the GAM Web Interstitial. Configured via globalAuctionContext.interstitial.

const moliConfig: Moli.MoliConfig = {
  slots: [
    {
      domId: 'interstitial_1',
      adUnitPath: '/1234/interstitial_1',
      sizes: [[1, 1]],
      position: 'interstitial',
      behaviour: { loaded: 'eager' },
      sizeConfig: []
    }
  ],
  globalAuctionContext: {
    interstitial: {
      enabled: true,
      adUnitPath: '/1234/interstitial_1',
      domId: 'interstitial_1',
      priority: ['c', 'gam']
    }
  }
};

See Traffic web interstitials for more information.

anchor-bottom / anchor-top​

Hybrid: waterfall between a custom (prebid) sticky element and the GAM Anchor format. Configured via globalAuctionContext.anchorBottomMobile / anchorBottomDesktop / anchorTop - independent waterfall state per position. The two bottom configs are disambiguated by domId (mobile_stickyad vs floorad), so both can run at once on a responsive page.

const moliConfig: Moli.MoliConfig = {
  slots: [
    {
      domId: 'mobile_stickyad',
      adUnitPath: '/1234/mobile_stickyad',
      sizes: [[320, 50]],
      position: 'anchor-bottom',
      behaviour: { loaded: 'eager' },
      sizeConfig: []
    }
  ],
  globalAuctionContext: {
    anchorBottomMobile: {
      enabled: true,
      adUnitPath: '/1234/mobile_stickyad',
      domId: 'mobile_stickyad',
      priority: ['gam', 'c']
    }
  }
};

See Traffic anchor ads on web and Collapsible anchor ads for web for more information.

Unsupported formats​

  • Rewarded ads (OutOfPageFormat.REWARDED) - not a slot position. Requested on demand via the rewardedAd() API instead.
  • Left / right side rails (LEFT_SIDE_RAIL / RIGHT_SIDE_RAIL) - not implemented.
  • Game manual interstitial (GAME_MANUAL_INTERSTITIAL) - not implemented.