The MediaStream.id read-only property is a string containing 36 characters denoting a unique identifier (GUID) for the object. 
 The MediaStream.id read-only property is a string containing 36 characters denoting a unique identifier (GUID) for the object. 
A string.
js
const promise = navigator.mediaDevices.getUserMedia({ audio: true, video: true, }); promise.then((stream) => { console.log(stream.id); });
| Specification | 
|---|
| Media Capture and Streams  # dom-mediastream-id  | 
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
id | 
26 | 12 | 41 | No | 15 | 11 | 4.4 | 26 | 41 | 14 | 11 | 1.5 | 
MediaStream, the interface this property belongs to.
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    https://developer.mozilla.org/en-US/docs/Web/API/MediaStream/id