video-ad-sdk/src/adContainer/helpers/getContentDocument.ts

VAST/VPAID SDK that allows video ads to be played on top of any player

export const getContentDocument = (
  iframeElement: HTMLIFrameElement
): Document | null =>
  iframeElement.contentDocument ||
  /* istanbul ignore next */
  (iframeElement.contentWindow && iframeElement.contentWindow.document)