使用oncanplay 属性定义何时可以开始播放音频/视频。
您可以尝试运行以下代码，以学习在媒体准备开始播放时如何执行脚本-
<!DOCTYPE html>
<html>
<body>
<video id = "myid" width = "320" height = "176" controls oncanplay="display()">
<source src = "/html5/foo.ogg" type = "video/ogg" />
<source src ="/html5/foo.mp4" type = "video/mp4" />
Your browser does not support the video element.
</video>
<script>
function display() {
alert("视频已加载！");
}
</script>
</body>
</html>