{"json_modified": "2016-09-29T15:54:02.628502", "uuid": "e9d19434-3307-4acb-8ed6-9b10ac1c6cdb", "title": "MediaTrackSupportedConstraints.deviceId", "url": "/en-US/docs/Web/API/MediaTrackSupportedConstraints/deviceId", "tags": ["Media Stream API", "API", "deviceId", "WebRTC", "Reference", "Constraints", "Property", "Web", "MediaTrackSupportedConstraints", "Media Capture and Streams API", "Media"], "translations": [], "modified": "2016-09-29T15:54:02", "label": "MediaTrackSupportedConstraints.deviceId", "localization_tags": [], "locale": "en-US", "id": 195991, "last_edit": "2016-09-29T15:53:56", "summary": "The <a href=\"/en-US/docs/Web/API/MediaTrackSupportedConstraints\" title=\"The MediaTrackSupportedConstraints dictionary establishes the list of constrainable properties recognized by the user agent or browser in its implementation of the MediaStreamTrack object. An object conforming to MediaTrackSupportedConstraints is returned by MediaDevices.getSupportedConstraints().\"><code>MediaTrackSupportedConstraints</code></a> dictionary's <strong><code>deviceId</code></strong> property is a read-only Boolean value which is present (and set to <code>true</code>) in the object returned by <a href=\"/en-US/docs/Web/API/MediaDevices/getSupportedConstraints\" title=\"The getSupportedConstraints() method of the MediaDevices interface returns an object based on the MediaTrackSupportedConstraints dictionary, whose member fields each specify one of the constrainable properties the user agent understands.\"><code>MediaDevices.getSupportedConstraints()</code></a> if and only if the <a class=\"glossaryLink\" href=\"/en-US/docs/Glossary/user_agent\" title=\"user agent: A user agent is a computer program representing a person, for example, a browser in a Web context.\">user agent</a> supports the <code>deviceId</code> constraint. If the constraint isn't supported, it's not included in the list, so this value will never be <code>false</code>.", "sections": [{"id": "Quick_Links", "title": null}, {"id": "Syntax", "title": "Syntax"}, {"id": "Value", "title": "Value"}, {"id": "Example", "title": "Example"}, {"id": "HTML_content", "title": "HTML content"}, {"id": "CSS_content", "title": "CSS content"}, {"id": "JavaScript_content", "title": "JavaScript content"}, {"id": "Result", "title": "Result"}, {"id": "Specifications", "title": "Specifications"}, {"id": "Browser_compatibility", "title": "Browser compatibility"}, {"id": "See_also", "title": "See also"}], "slug": "Web/API/MediaTrackSupportedConstraints/deviceId", "review_tags": []}