HTML5是一項功能強大的技術，其中包括視頻全屏的功能。下面是實現HTML5視頻全屏的基本代碼：
HTML5視頻在全屏模式下的頁面代碼：
<!DOCTYPE html>
<html>
<head>
<title>HTML5視頻全屏模式</title>
</head>
<body>
<video id="myvideo" width="640" height="360">
<source src="video.mp4" type="video/mp4">
</video>
<button onclick="toggleFullScreen()">全屏</button>
<script>
function toggleFullScreen() {
var videoElem = document.getElementById("myvideo");
if (!document.fullscreenElement) {
videoElem.requestFullscreen().catch(err =>{
alert(`Error attempting to enable full-screen mode: ${err.message} (${err.name})`);
});
} else {
document.exitFullscreen().catch(err =>{
alert(`Error attempting to exit full-screen mode: ${err.message} (${err.name})`);
});
}
}
</script>
</body>
</html>