html5 video fullscreen

function toggleFullScreen() {
  var doc = window.document;
  var elem = doc.body; //the element you want to make fullscreen

  var requestFullScreen = elem.requestFullscreen || elem.webkitRequestFullScreen || elem.mozRequestFullScreen || elem.msRequestFullscreen;
  var cancelFullScreen = doc.exitFullscreen || doc.webkitExitFullscreen || doc.mozCancelFullScreen|| doc.msExitFullscreen;

  if(!(doc.fullscreenElement || doc.mozFullScreenElement || doc.webkitFullscreenElement || doc.msFullscreenElement)) {
      requestFullScreen.call(doc.body);
  }
  else {
    cancelFullScreen.call(doc);
  }
}