動画と音声を操作する

このページに埋め込まれているコード

<video id="video" controls autoplay loop>
  <source src="video.mp4">
  <source src="video.webm">
</video>
<script>
function isFullScreen() {
  return (document.fullScreen == true || document.mozFullScreen === true || document.webkitIsFullScreen === true);
}

function requestFullScreen(element) {
  if (element.requestFullScreen) {
    element.requestFullScreen();
  } else if (element.mozRequestFullScreen) {
    element.mozRequestFullScreen();
  } else if (element.webkitRequestFullScreen) {
    element.webkitRequestFullScreen();
  }
}

function cancelFullScreen() {
  if (document.cancelFullScreen) {
    document.cancelFullScreen();
  } else if (document.mozCancelFullScreen) {
    document.mozCancelFullScreen();
  } else if (document.webkitCancelFullScreen) {
    document.webkitCancelFullScreen();
  }
}

var video = document.getElementById('video');
video.addEventListener('loadedmetadata', function() {
  document.addEventListener('keydown', function(event) {
    switch (event.keyCode) {
      case 32: // space
        (video.paused) ? video.play() : video.pause();
        event.preventDefault();
        break;
      case 39: // right
        video.currentTime += 5;
        event.preventDefault();
        break;
      case 37: // left
        video.currentTime -= 5;
        event.preventDefault();
        break;
      case 13: // Enter
        isFullScreen() ? cancelFullScreen() : requestFullScreen(video);
        break;
    }
  }, false);
}, false);
</script>
    

Enterキー・カーソルキー・スペースキーを押して動作を確認してみてください