MediaTrackConstraints.deviceId

The MediaTrackConstraints dictionary's deviceId property is a ConstrainDOMString describing the requested or mandatory constraints placed upon the value of the deviceId constrainable property.

If needed, you can determine whether or not this constraint is supported by checking the value of MediaTrackSupportedConstraints.deviceId as returned by a call to MediaDevices.getSupportedConstraints(). However, typically this is unnecessary since browsers will simply ignore any constraints they're unfamiliar with.

Because RTP doesn't include this information, tracks associated with a WebRTC RTCPeerConnection will never include this property.

Syntax

var constraintsObject = { deviceId: constraint };

constraintsObject.deviceId = constraint;

Value

An object based on ConstrainDOMString specifying one or more acceptable, ideal, and/or exact (mandatory) device IDs which are acceptable as the source of media content.

Device IDs are unique for a given origin, and are guaranteed to be the same across browsing sessions on the same origin. However, the value of the deviceId is determined by the source of the track's content, and there's no particular format mandated by the specification (although some kind of GUID is recommended). That means that a given track will only return one value for the deviceId when you call getCapabilities().

Because of this, there's no use for the device ID when calling MediaStreamTrack.applyConstraints(), since there is only one possible value; however, you can record a deviceId and use it to ensure that you get the same source for multiple calls to getUserMedia().

An exception to the rule that device IDs are the same across browsing sessions: private browsing mode will use a different ID, and will change it each browsing session.

Example

See Example: Constraint exerciser in Capabilities, constraints, and settings for an example.

Specifications

Specification Status Comment
Media Capture and Streams
The definition of 'deviceId' in that specification.
Candidate Recommendation Initial specification.

Browser compatibility

DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
deviceIdChrome Full support 59Edge Full support ≤79Firefox Full support 36
Notes
Full support 36
Notes
Notes Prior to Firefox 69, Firefox only supported deviceId in constraints passed into getUserMedia().
IE No support NoOpera Full support YesSafari ? WebView Android Full support 59Chrome Android Full support 59Firefox Android Full support 36
Notes
Full support 36
Notes
Notes Firefox for Android only supports deviceId when used in constraints passed into getUserMedia().
Opera Android ? Safari iOS ? Samsung Internet Android Full support 7.0

Legend

Full support
Full support
No support
No support
Compatibility unknown
Compatibility unknown
See implementation notes.
See implementation notes.

See also