MediaTrackSupportedConstraints.volume - Web APIs 编辑

Obsolete

This feature is obsolete.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.

The 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 user agent supports the 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().

Syntax

volumeConstraintSupported = supportedConstraintsDictionary.volume;

Value

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.

Example

HTML content

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

CSS content

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

JavaScript content

let result = document.getElementById("result");

if (navigator.mediaDevices.getSupportedConstraints().volume) {
  result.textContent = "Supported!";
} else {
  result.textContent = "Not supported!";
}

Result

Browser compatibility

BCD tables only load in the browser

See also

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