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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

MediaStream.getTrackById() 方法返回 MediaStreamTrack object representing the track with the specified ID string. If there is no track with the specified ID, this method returns null .

句法

var track = MediaStream.getTrackById(id);
					

参数

id

DOMString which identifies the track to be returned.

返回值

If a track is found for which MediaStreamTrack.id matches the specified id string, that MediaStreamTrack object is returned. Otherwise, the returned value is null .

范例

This example activates a commentary track on a video by ducking the audio level of the main audio track to 50%, then enabling the commentary track.

stream.getTrackById("primary-audio-track").applyConstraints({ volume: 0.5 });
stream.getTrackById("commentary-track").enabled = true;
					

规范

规范	状态	注释
媒体捕获和流 The definition of 'getTrackById()' in that specification.	候选推荐	最初的规范。

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
getTrackById	Chrome 26	Edge 12	Firefox 49	IE No	Opera No	Safari Yes	WebView Android 37	Chrome Android 26	Firefox Android 49	Opera Android No	Safari iOS Yes	Samsung Internet Android 1.5

图例

完整支持

完整支持

不支持

不支持

另请参阅

• MediaStream
• MediaStreamTrack.id

元数据

• 最后修改： 2020 年 1 月 22 日

相关话题

1. Media Streams API
2. MediaStream
3. 构造函数

   1. MediaStream()
4. 特性

   1. active
   2. ended
   3. id
   4. onaddtrack
   5. onremovetrack
5. 方法

   1. addTrack()
   2. clone()
   3. getAudioTracks()
   4. getTrackById()
   5. getTracks()
   6. getVideoTracks()
6. 事件

   1. addtrack
   2. removetrack
7. 继承：

   1. EventTarget
8. Related pages for Media Capture and Streams

   1. AudioStreamTrack
   2. BlobEvent
   3. CanvasCaptureMediaStream
   4. ConstrainBoolean
   5. ConstrainDOMString
   6. ConstrainDouble
   7. ConstrainLong
   8. DoubleRange
   9. HTMLCanvasElement.captureStream()
   10. LongRange
   11. MediaDevices
   12. MediaStreamTrack
   13. MediaStreamTrackEvent
   14. MediaTrackCapabilities
   15. MediaTrackConstraints
   16. MediaTrackSettings
   17. MediaTrackSupportedConstraints
   18. Navigator.mediaDevices
   19. NavigatorUserMedia
   20. NavigatorUserMediaError
   21. VideoStreamTrack
   22. navigator.mediaDevices.getUserMedia()