IPlayerServer

let sessionId1: IPlayerSessionId = { id: 1 };
let mediaPlayer1: HtmlMediaElement | VideoPlayer | AudioPlayer; // say associated with sessionId 1.
let sessionId2: IPlayerSessionId = { id: 2 };
let mediaPlayer2: HtmlMediaElement | VideoPlayer | AudioPlayer; // say associated with sessionId 2.

private getBufferedRanges(mediaPlayer: HtmlMediaElement | VideoPlayer | AudioPlayer): Array<ITimeRange> {
  const result: Array<ITimeRange> = [];
  const bufferedTimeRanges = mediaPlayer.buffered;
  for (let i = 0; i < bufferedTimeRanges.length; ++i) {
    result.push({
      start: bufferedTimeRanges.start(i),
      end: bufferedTimeRanges.end(i)
    });
  }
  return result;
}

playerServerRef.current?.updateBufferedRanges(getBufferedRanges(mediaPlayer1), sessionId1);
playerServerRef.current?.updateBufferedRanges(getBufferedRanges(mediaPlayer2), sessionId2);

let media = useRef<VideoPlayer | AudioPlayer | null>(...);
let sessionId = useRef<IPlayerSessionId | undefined>(...);

const onAudioTrackAdded = (event: Event): void => {
  if (event instanceof TrackEvent) {
    let track = (event as TrackEvent).track;
    if (track !== undefined) {
      playerServerRef.current?.addTrack({
        id: track.id,
        type: "AUDIO",
        kind: track.kind,
        label: track.label,
        language: track.language,
        enabled: (track as AudioTrack).enabled
      }, sessionId.current);
      // Do other operations if needed.
    } else {
      console.error("Undefined audio track.");
    }
  }
}

const onVideoTrackAdded = (event: Event): void => {
  if (event instanceof TrackEvent) {
    let track = (event as TrackEvent).track;
    if (track !== undefined) {
      playerServerRef.current?.addTrack({
        id: track.id,
        type: "VIDEO",
        kind: track.kind,
        label: track.label,
        language: track.language,
        enabled: (track as VideoTrack).selected
      }, sessionId.current);
      // Do other operations if needed.
    } else {
      console.error("Undefined video track.");
    }
  }
}

const onTextTrackAdded = (event: Event): void => {
  if (event instanceof TrackEvent) {
    let track = (event as TrackEvent).track;
    if (track !== undefined) {
      playerServerRef.current?.addTrack({
        id: track.id,
        type: "TEXT",
        kind: track.kind,
        label: track.label,
        language: track.language,
        mode: (track as TextTrack).mode
      }, sessionId.current);
      // Do other operations if needed.
    } else {
      console.error("Undefined text track.");
    }
  }
}

media.current?.audioTracks.addEventListener("addtrack", onAudioTrackAdded);
media.current?.videoTracks.addEventListener("addtrack", onVideoTrackAdded);
media.current?.textTracks.addEventListener("addtrack", onTextTrackAdded);

let media = useRef<VideoPlayer | AudioPlayer | null>(...);
let sessionId = useRef<IPlayerSessionId | undefined>(...);

const onAudioTrackRemoved = (event: Event): void => {
  if (event instanceof TrackEvent) {
    let track = (event as TrackEvent).track;
    if (track !== undefined) {
      playerServerRef.current?.removeTrack({
        id: track.id,
        type: "AUDIO",
        kind: track.kind,
        label: track.label,
        language: track.language,
        enabled: (track as AudioTrack).enabled
      }, sessionId.current);
      // Do other operations if needed.
    } else {
      console.error("Undefined audio track.");
    }
  }
}

const onVideoTrackRemoved = (event: Event): void => {
  if (event instanceof TrackEvent) {
    let track = (event as TrackEvent).track;
    if (track !== undefined) {
      playerServerRef.current?.removeTrack({
        id: track.id,
        type: "VIDEO",
        kind: track.kind,
        label: track.label,
        language: track.language,
        enabled: (track as VideoTrack).selected
      }, sessionId.current);
      // Do other operations if needed.
    } else {
      console.error("Undefined video track.");
    }
  }
}

const onTextTrackRemoved = (event: Event): void => {
  if (event instanceof TrackEvent) {
    let track = (event as TrackEvent).track;
    if (track !== undefined) {
      playerServerRef.current?.removeTrack({
        id: track.id,
        type: "TEXT",
        kind: track.kind,
        label: track.label,
        language: track.language,
        mode: (track as TextTrack).mode
      }, sessionId.current);
      // Do other operations if needed.
    } else {
      console.error("Undefined text track.");
    }
  }
}

media.current?.audioTracks.addEventListener("removetrack", onAudioTrackRemoved);
media.current?.videoTracks.addEventListener("removetrack", onVideoTrackRemoved);
media.current?.textTracks.addEventListener("removetrack", onTextTrackRemoved);