在此页

• 句法
• 范例
• 浏览器兼容性
• 另请参阅
• 相关话题

过时
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

MediaTrackSupportedConstraints dictionary's volume property is a read-only Boolean value which is present (and set to true ) in the object returned by MediaDevices.getSupportedConstraints() if and only if the 用户代理 支持 volume constraint. If the constraint isn't supported, it's not included in the list, so this value will never be false .

You can access the supported constraints dictionary by calling navigator.mediaDevices.getSupportedConstraints() .

句法

volumeConstraintSupported = supportedConstraintsDictionary.volume;
					

值

This property is present in the dictionary (and its value is always true ) if the user agent supports the volume constraint. If the property isn't present, this property is missing from the supported constraints dictionary, and you'll get undefined if you try to look at its value.

范例

HTML 内容

<div id="result">
</div>
					

CSS content

#result {
  font: 14px "Arial", sans-serif;
}
					

JavaScript 内容

let result = document.getElementById("result");
if (navigator.mediaDevices.getSupportedConstraints().volume) {
  result.innerHTML = "Supported!";
} else {
  result.innerHTML = "Not supported!";
}
					

结果

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
volume 弃用 非标	Chrome 52	Edge ≤79	Firefox No	IE ?	Opera Yes	Safari ?	WebView Android 52	Chrome Android 52	Firefox Android No	Opera Android Yes	Safari iOS ?	Samsung Internet Android 6.0

图例

完整支持

完整支持

不支持

不支持

兼容性未知 ?

兼容性未知

非标。预期跨浏览器支持较差。

非标。预期跨浏览器支持较差。

弃用。不要用于新网站。

弃用。不要用于新网站。

另请参阅

• Media Capture and Streams API
• MediaDevices.getSupportedConstraints()
• MediaTrackSupportedConstraints
• MediaStreamTrack

元数据

• 最后修改： Jan 25, 2020

相关话题

1. Media Streams API
2. MediaTrackSupportedConstraints
3. 特性

   1. aspectRatio
   2. autoGainControl
   3. channelCount
   4. cursor
   5. deviceId
   6. displaySurface
   7. echoCancellation
   8. facingMode
   9. frameRate
   10. groupId
   11. height
   12. latency
   13. noiseSuppression
   14. sampleRate
   15. sampleSize
   16. volume
4. 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. MediaStream
   13. MediaStreamTrack
   14. MediaStreamTrackEvent
   15. MediaTrackCapabilities
   16. MediaTrackConstraints
   17. MediaTrackSettings
   18. Navigator.mediaDevices
   19. NavigatorUserMedia
   20. NavigatorUserMediaError
   21. VideoStreamTrack
   22. navigator.mediaDevices.getUserMedia()