getFullScreenApis = () => {

  const d = document,
    db = d.body,
    result = {
      '_requestFullscreen': db.webkitRequestFullscreen !== undefined ? 'webkitRequestFullscreen' :
              db.mozRequestFullScreen !== undefined ? 'mozRequestFullScreen' :
              db.msRequestFullscreen !== undefined ? 'msRequestFullscreen' :
              db.requestFullscreen !== undefined ? 'requestFullscreen' : '',
      '_exitFullscreen': d.webkitExitFullscreen !== undefined ? 'webkitExitFullscreen' :
              d.mozCancelFullScreen !== undefined ? 'mozCancelFullScreen' :
              d.msExitFullscreen !== undefined ? 'msExitFullscreen' :
              d.exitFullscreen !== undefined ? 'exitFullscreen' : '',
      '_fullscreenElement': d.webkitFullscreenElement !== undefined ? 'webkitFullscreenElement' :
              d.mozFullScreenElement !== undefined ? 'mozFullScreenElement' :
              d.msFullscreenElement !== undefined ? 'msFullscreenElement' :
              d.fullscreenElement !== undefined ? 'fullscreenElement' : '',
      '_fullscreenChange': d.webkitFullscreenElement !== undefined ? 'webkitfullscreenchange' :
              d.mozFullScreenElement !== undefined ? 'mozfullscreenchange' :
              d.msFullscreenElement !== undefined ? 'MSFullscreenChange' :
              d.fullscreenElement !== undefined ? 'fullscreenchange' : ''
    };
  if (!result._requestFullscreen || !result._exitFullscreen || !result._fullscreenElement) {
    return null;
  } else {
    return result;
  }

}
TW-Code
@deprecated delete this in 2016 and use $tw.utils.getFullScreenApis instead