javascript - 试图获得完整的视频时长但以 Nan 身份返回

Question

我正在尝试获取我的播放器的视频持续时间，但它返回 NaN，我不确定如何从此处访问它。

<video id="videoPlayerNew" class="video-js vjs-default-skin vjs-controls-enabled" poster="http://camendesign.com/code/video_for_everybody/poster.jpg" data-setup="{}" controls="">
    <source src="sample.mp4" type="video/mp4">
    <p class="vjs-no-js">Javascript was disabled or not supported</p>
</video>

<script>
    var vid = document.getElementById("videoPlayerNew");
    console.log(vid.duration);
</script>

日志告诉我:NaN

Answer 1

等待onloadedmetadata事件，loadedmetadata 事件在加载元数据 时触发。

var myVideo = document.getElementById("videoPlayerNew");
myVideo.onloadedmetadata = function() {
  console.log('metadata loaded!');
  console.log(this.duration);//this refers to myVideo
};

<video id="videoPlayerNew" class="video-js vjs-default-skin vjs-controls-enabled" poster="http://camendesign.com/code/video_for_everybody/poster.jpg" data-setup="{}" controls="">
  <source src="http://www.w3schools.com/html/mov_bbb.mp4" type="video/mp4">
    <p class="vjs-no-js">Javascript was disabled or not supported</p>
</video>