{"json_modified": "2016-10-20T16:18:03.662063", "uuid": "bc961319-d9d6-4b5c-ae5b-d81ba29008dd", "title": "MediaTrackConstraints.deviceId", "url": "/en-US/docs/Web/API/MediaTrackConstraints/deviceId", "tags": ["API", "deviceId", "WebRTC", "Reference", "Constraints", "Property", "Media Streams API", "getusermedia", "MediaTrackConstraints", "Media Capture and Streams API", "Media"], "translations": [], "modified": "2016-10-20T16:18:03", "label": "MediaTrackConstraints.deviceId", "localization_tags": [], "locale": "en-US", "id": 196723, "last_edit": "2016-10-20T16:17:56", "summary": "The <a href=\"/en-US/docs/Web/API/MediaTrackConstraints\" title=\"The MediaTrackConstraints dictionary is used to describe a set of capabilities and the value or values each can take on. A constraints dictionary is passed into applyConstraints() to allow a script to establish a set of exact (required) values or ranges and/or preferred values or ranges of values for the track, and the most recently-requested set of custom constraints can be retrieved by calling getConstraints().\"><code>MediaTrackConstraints</code></a> dictionary's <code><strong>deviceId</strong></code> property is a <a href=\"/en-US/docs/Web/API/ConstrainDOMString\" title=\"The ConstrainDOMString dictionary is used to specify a constraint for a property whose value is a string. It allows you to specify one or more exact string values from which one must be the parameter's value, or a set of ideal values which should be used if possible. You can also specify a single string (or an array of strings) which the user agent will do its best to match once all more stringent constraints have been applied.\"><code>ConstrainDOMString</code></a> describing the requested or mandatory constraints placed upon the value of the <a href=\"/en-US/docs/Web/API/MediaTrackSettings/deviceId\" title=\"The MediaTrackSettings dictionary's deviceId property is a DOMString which uniquely identifies the source for the corresponding MediaStreamTrack for the origin corresponding to the browsing session. This lets you determine what value was selected to comply with your specified constraints for this property's value as described in the MediaTrackConstraints.deviceId property you provided when calling either getUserMedia().\"><code>deviceId</code></a> constrainable property.", "sections": [{"id": "Quick_Links", "title": null}, {"id": "Syntax", "title": "Syntax"}, {"id": "Value", "title": "Value"}, {"id": "Example", "title": "Example"}, {"id": "Specifications", "title": "Specifications"}, {"id": "Browser_compatibility", "title": "Browser compatibility"}, {"id": "See_also", "title": "See also"}], "slug": "Web/API/MediaTrackConstraints/deviceId", "review_tags": []}