Add getActiveAudioOutputDevice to room API (livekit#500)

* add getActiveAudioOutputDevice to room API

* add changeset

* run prettier

* return an empty string if no audiooutput device was set

.changeset/rotten-pumpkins-share.md

@@ -0,0 +1,5 @@
+---
+'livekit-client': minor
+---
+
+add getActiveAudioOutputDevice method to Room

src/room/Room.ts

@@ -570,7 +570,18 @@ class Room extends (EventEmitter as new () => TypedEmitter<RoomEventCallbacks>)
   }
 
   /**
-   * Switches all active device used in this room to the given device.
+   * Returns the active audio output device used in this room.
+   *
+   * Note: to get the active `audioinput` or `videoinput` use [[LocalTrack.getDeviceId()]]
+   *
+   * @return the previously successfully set audio output device ID or an empty string if the default device is used.
+   */
+  getActiveAudioOutputDevice(): string {
+    return this.options.audioOutput?.deviceId ?? '';
+  }
+
+  /**
+   * Switches all active devices used in this room to the given device.
    *
    * Note: setting AudioOutput is not supported on some browsers. See [setSinkId](https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement/setSinkId#browser_compatibility)
    *
@@ -612,16 +623,10 @@ class Room extends (EventEmitter as new () => TypedEmitter<RoomEventCallbacks>)
       this.options.audioOutput ??= {};
       const prevDeviceId = this.options.audioOutput.deviceId;
       this.options.audioOutput.deviceId = deviceId;
-      const promises: Promise<void>[] = [];
-      this.participants.forEach((p) => {
-        promises.push(
-          p.setAudioOutput({
-            deviceId,
-          }),
-        );
-      });
       try {
-        await Promise.all(promises);
+        await Promise.all(
+          Array.from(this.participants.values()).map((p) => p.setAudioOutput({ deviceId })),
+        );
       } catch (e) {
         this.options.audioOutput.deviceId = prevDeviceId;
         throw e;