MediaStream.id is a read-only string of 36 characters — a unique identifier (GUID) for that stream object (MDN).
Read the notes below before you rely on this property. Prefer feature detection when support is limited.
Use stream.id. Start with this line.
stream.id| Call | What it does |
|---|---|
stream.id | Primary signature. |
Built into the browser. Read stream.id on a MediaStream — no import required.
stream.idThis member has no parameters beyond those shown in the signature.
| Return Value | Description |
|---|---|
| * | 36-character unique GUID string |
idEven a stream with no tracks gets a unique GUID.
const stream = new MediaStream();
console.log(stream.getTracks().length); // 0
console.log(stream.id.length); // 36
console.log(stream.id); // e.g. "…-…-…-…-…"Confirm length and hyphenated UUID pattern on a canvas stream.
const canvas = document.createElement("canvas");
const stream = canvas.captureStream();
const uuidLike = /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
console.log(stream.id.length); // 36
console.log(uuidLike.test(stream.id)); // true
console.log(stream.id);captureStream() creates a stream. No camera prompt.Log the id of a camera/microphone stream.
navigator.mediaDevices
.getUserMedia({ audio: true, video: true })
.then((stream) => {
console.log(stream.id);
});stream.id. MDN’s basic example.MapKey a registry by stream.id — each stream stays unique.
const streamsById = new Map();
const canvas = document.createElement("canvas");
function register(stream) {
streamsById.set(stream.id, stream);
}
const a = canvas.captureStream();
const b = canvas.captureStream();
register(a);
register(b);
console.log(streamsById.size); // 2
console.log(a.id === b.id); // falseMap keys must be unique.stream.id vs track.idThe stream and its tracks have separate identifiers.
const canvas = document.createElement("canvas");
const stream = canvas.captureStream();
const track = stream.getVideoTracks()[0];
console.log(stream.id);
console.log(track.id);
console.log(stream.id === track.id); // falseMediaStream.id is Baseline Widely available (MDN, since September 2017). Safe for modern media apps.
Supported across Chrome, Firefox, Safari, Edge, and Opera. Read-only 36-character GUID string for each MediaStream.
Bottom line: Use freely as a unique key. Prefer canvas.captureStream for demos without camera permission.
Learn how to create a MediaStream with new MediaStream().
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