JavaScript/TypeScript client SDK for LiveKit

livekit-client is the official client SDK for LiveKit. With it, you can add real time video and audio to your web apps.

Docs

Docs and guides at https://docs.livekit.io

SDK reference

Installation

Yarn

yarn add livekit-client

NPM

npm install livekit-client --save

Usage

Examples below are in TypeScript, if using JS/CommonJS imports replace import with:

const livekit = require('livekit-client');

const room = new livekit.Room(...);
await room.connect(...);

Connecting to a room, publish video & audio

import {
  connect,
  RoomEvent,
  RemoteParticipant,
  RemoteTrackPublication,
  RemoteTrack,
  Participant,
} from 'livekit-client';

// creates a new room with options
const room = new Room({
  // automatically manage subscribed video quality
  adaptiveStream: true,

  // optimize publishing bandwidth and CPU for simulcasted tracks
  dynacast: true,

  // default capture settings
  videoCaptureDefaults: {
    resolution: VideoPresets.hd.resolution,
  }
});

// set up event listeners
room
    .on(RoomEvent.TrackSubscribed, handleTrackSubscribed)
    .on(RoomEvent.TrackUnsubscribed, handleTrackUnsubscribed)
    .on(RoomEvent.ActiveSpeakersChanged, handleActiveSpeakerChange)
    .on(RoomEvent.Disconnected, handleDisconnect)
    .on(RoomEvent.LocalTrackUnpublished, handleLocalTrackUnpublished);

// connect to room
await room.connect('ws://localhost:7800', token, {
  // don't subscribe to other participants automatically
  autoSubscribe: false,
});
console.log('connected to room', room.name);

// publish local camera and mic tracks
await room.localParticipant.enableCameraAndMicrophone();

function handleTrackSubscribed(
  track: RemoteTrack,
  publication: RemoteTrackPublication,
  participant: RemoteParticipant
) {
  if (track.kind === Track.Kind.Video || track.kind === Track.Kind.Audio) {
    // attach it to a new HTMLVideoElement or HTMLAudioElement
    const element = track.attach();
    parentElement.appendChild(element);
  }
}

function handleTrackUnsubscribed(
  track: RemoteTrack,
  publication: RemoteTrackPublication,
  participant: RemoteParticipant
) {
  // remove tracks from all attached elements
  track.detach();
}

function handleLocalTrackUnpublished(
  track: LocalTrackPublication,
  participant: LocalParticipant,
) {
  // when local tracks are ended, update UI to remove them from rendering
  track.detach();
}

function handleActiveSpeakerChange(speakers: Participant[]) {
  // show UI indicators when participant is speaking
}

function handleDisconnect() {
  console.log('disconnected from room');
}

In order to connect to a room, you need to first create an access token.

See access token docs for details

Handling common track types

While LiveKit is designed to be flexible, we've added a few shortcuts that makes working with common track types simple. For a user's camera, microphone, and screen share, you can enable them with the following LocalParticipant methods:

const p = room.localParticipant;
// turn on the local user's camera and mic, this may trigger a browser prompt
// to ensure permissions are granted
await p.setCameraEnabled(true);
await p.setMicrophoneEnabled(true);

// start sharing the user's screen, this will trigger a browser prompt to select
// the screen to share.
await p.setScreenShareEnabled(true);

// disable camera to mute them, when muted, the user's camera indicator will be turned off
await p.setCameraEnabled(false);

Similarly, you can access these common track types on the other participants' end.

// get a RemoteParticipant by their sid
const p = room.participants.get('participant-sid');
if (p) {
  // if the other user has enabled their camera, attach it to a new HTMLVideoElement
  if (p.isCameraEnabled) {
    const track = p.getTrack(Track.Source.Camera);
    if (track?.isSubscribed) {
      const videoElement = track.videoTrack?.attach()
      // do something with the element
    }
  }
}

Creating a track prior to creating a room

In some cases, it may be useful to create a track before creating a room. For example, when building a staging area so the user may check their own camera.

You can use our global track creation functions for this:

const tracks = await createLocalTracks({
  audio: true,
  video: true,
});

Publish tracks from any source

LiveKit lets you publish any track as long as it can be represented by a MediaStreamTrack. You can specify a name on the track in order to identify it later.

const pub = await room.localParticipant.publishTrack(mediaStreamTrack, {
  name: 'mytrack',
  simulcast: true,
  // if this should be treated like a camera feed, tag it as such
  // supported known sources are .Camera, .Microphone, .ScreenShare
  source: Track.Source.Camera,
})

// you may mute or unpublish the track later
pub.setMuted(true);

room.localParticipant.unpublishTrack(mediaStreamTrack)

Device management APIs

Users may have multiple input and output devices available. LiveKit will automatically use the one that's deemed as the default device on the system. You may also list and specify an alternative device to use.

We use the same deviceId as one returned by MediaDevices.enumerateDevices().

Example listing and selecting a camera device

// list all microphone devices
const devices = await Room.getLocalDevices('audioinput');

// select last device
const device = devices[devices.length-1];

// in the current room, switch to the selected device and set
// it as default audioinput in the future.
await room.switchActiveDevice('audioinput', device.deviceId);

You can also switch devices given a constraint. This could be useful on mobile devices to switch to a back-facing camera:

await videoTrack.restartTrack({
  facingMode: 'environment',
});

Handling device failures

When creating tracks using LiveKit APIs (connect, createLocalTracks, setCameraEnabled, etc), it's possible to encounter errors with the underlying media device. In those cases, LiveKit will emit RoomEvent.MediaDevicesError.

You can use the helper MediaDeviceFailure.getFailure(error) to determine specific reason for the error.

PermissionDenied - the user disallowed capturing devices
NotFound - the particular device isn't available
DeviceInUse - device is in use by another process (happens on Windows)

These distinctions enables you to provide more specific messaging to the user.

You could also retrieve the last error with LocalParticipant.lastCameraError and LocalParticipant.lastMicrophoneError.

Audio playback

Browsers can be restrictive with regards to audio playback that is not initiated by user interaction. What each browser considers as user interaction can vary by vendor (for example, Safari on iOS is very restrictive).

LiveKit will attempt to autoplay all audio tracks when you attach them to audio elements. However, if that fails, we'll notify you via RoomEvent.AudioPlaybackStatusChanged. Room.canPlayAudio will indicate if audio playback is permitted. LiveKit takes an optimistic approach so it's possible for this value to change from true to false when we encounter a browser error.

In the case user interaction is required, LiveKit provides Room.startAudio to start audio playback. This function must be triggered in an onclick or ontap event handler. In the same session, once audio playback is successful, additional audio tracks can be played without further user interactions.

room.on(RoomEvent.AudioPlaybackStatusChanged, () => {
  if (!room.canPlayAudio) {
    // UI is necessary.
    ...
    button.onclick = () => {
      // startAudio *must* be called in an click/tap handler.
      room.startAudio().then(() => {
        // successful, UI can be removed now
        button.remove();
      });
    }
  }
});

Configuring logging

This library uses loglevel for its internal logs. You can change the effective log level with the logLevel field in ConnectOptions.

Examples

SDK Sample

example/sample.ts contains a demo webapp that uses the SDK. Run it with yarn sample

Browser Support

Browser	Desktop OS	Mobile OS
Chrome	Windows, macOS, Linux	Android
Firefox	Windows, macOS, Linux	Android
Safari	macOS	iOS
Edge (Chromium)	Windows, macOS

caiiiycuk / client-sdk-js