视频无法在iframe标签中全屏播放

<video src="video.mp4" controls></video>

var video = document.querySelector('video');

function toggleFullScreen() {
  if (video.requestFullscreen) {
    video.requestFullscreen();
  } else if (video.mozRequestFullScreen) {
    video.mozRequestFullScreen();
  } else if (video.webkitRequestFullscreen) {
    video.webkitRequestFullscreen();
  } else if (video.msRequestFullscreen) {
    video.msRequestFullscreen();
  }
}

// 在全屏状态下按下Esc键退出全屏
document.addEventListener('keydown', function(event) {
  if (event.key === 'Escape') {
    exitFullScreen();
  }
});

// 退出全屏
function exitFullScreen() {
  if (document.exitFullscreen) {
    document.exitFullscreen();
  } else if (document.mozCancelFullScreen) {
    document.mozCancelFullScreen();
  } else if (document.webkitExitFullscreen) {
    document.webkitExitFullscreen();
  } else if (document.msExitFullscreen) {
    document.msExitFullscreen();
  }
}