HTMLMediaElement.textTracks

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只读 textTracks property on HTMLMediaElement objects returns a TextTrackList object listing all of the TextTrack objects representing the media element's text tracks , in the same order as in the list of text tracks.

You can detect when tracks are added to and removed from an <audio> or <video> element using the addtrack and removetrack events. However, these events aren't sent directly to the media element itself. Instead, they're sent to the track list object of the HTMLMediaElement that corresponds to the type of track that was added to the element

The returned list is live ; that is, as tracks are added to and removed from the media element, the list's contents change dynamically. Once you have a reference to the list, you can monitor it for changes to detect when new text tracks are added or existing ones removed.

见 Event handlers in TextTrackList to learn more about watching for changes to a media element's track list.

句法

var textTracks = mediaElement.textTracks;

值

A TextTrackList object representing the list of text tracks included in the media element. The list of tracks can be accessed using array notation, or using the object's getTrackById() 方法。

Each track is represented by a TextTrack object which provides information about the track.

范例

We start with a <video> that has several <track> children

<video controls poster="/images/sample.gif">
  <source src="sample.mp4" type="video/mp4">
  <source src="sample.ogv" type="video/ogv">
  <track kind="captions" src="sampleCaptions.vtt" srclang="en">
  <track kind="descriptions" src="sampleDescriptions.vtt" srclang="en">
  <track kind="chapters" src="sampleChapters.vtt" srclang="en">
  <track kind="subtitles" src="sampleSubtitles_de.vtt" srclang="de">
  <track kind="subtitles" src="sampleSubtitles_en.vtt" srclang="en">
  <track kind="subtitles" src="sampleSubtitles_ja.vtt" srclang="ja">
  <track kind="subtitles" src="sampleSubtitles_oz.vtt" srclang="oz">
  <track kind="metadata" src="keyStage1.vtt" srclang="en" label="Key Stage 1">
  <track kind="metadata" src="keyStage2.vtt" srclang="en" label="Key Stage 2">
  <track kind="metadata" src="keyStage3.vtt" srclang="en" label="Key Stage 3">
</video>

HTMLMediaElement .textTracks 返回 textTracksList thru which we can iterate. Here we print all the properties of each English track to the console.

var tracks = document.querySelector('video').textTracks;
for (var i = 0, L = tracks.length; i < L; i++) { /* tracks.length == 10 */
   if (tracks[i].language == 'en') {
      console.dir(tracks[i]);
   }
}

Properties & Methods

properties

length: Returns the number of text tracks in TextTrackList 对象。

方法

getTrackById(): getTrackById( id ) method returns the first TextTrack 在 TextTrackList object that matches the id, or null if there is no match.

规范

规范	状态	注释
HTML 实时标准 The definition of 'HTMLMediaElement.textTracks' in that specification.	实时标准	无变化自 HTML5
HTML5 The definition of 'HTMLMediaElement.textTracks' in that specification.	推荐	初始定义。

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`textTracks`	Chrome Yes	Edge 12	Firefox Yes	IE ?	Opera Yes	Safari Yes	WebView Android ?	Chrome Android ?	Firefox Android ?	Opera Android ?	Safari iOS ?	Samsung Internet Android ?

图例

完整支持
兼容性未知 ?

另请参阅

The interface defining it, HTMLMediaElement .
<video> and <audio>
VideoTrack and VideoTrackList
AudioTrack and AudioTrackList
VideoTrackList change , addtrack and removetrack events
Audio TrackList change , addtrack and removetrack events

元数据

最后修改： May 31, 2019

在此页

句法

值

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Properties & Methods

properties

方法

规范

浏览器兼容性

图例

另请参阅

相关话题