Join and Leave (Web SDK 4.x)

The Agora Web SDK uses the AgoraRTCClient object to manage the behavior of a local user in the target channel. Create an AgoraRTCClient object before joining the target channel.

Create an AgoraRTCClient object

Call AgoraRTC.createClient to create an AgoraRTCClient object. Specify the video codec type (codec) and the channel profile (mode) when creating AgoraRTCClient.

const client = AgoraRTC.createClient({
  codec: "vp8",
  mode: "rtc",
});

Choose the video codec type

The Agora Web SDK supports two video codec types: "vp8" (VP8) and "h264" (H.264). The codec setting only affects the video encoding type of the published video. For the subscriber, as long as it supports decoding the video codec type, the subscription can be completed successfully. For example, the desktop version of Chrome 58 or later supports both VP8 and H.264, while while Safari versions before 12.1 do not support VP8; if two hosts in a channel publish VP8 and H.264 videos, respectively, the audience using desktop Chrome 58 can decode the videos of both hosts, but the audience using Safari versions before 12.1 can only decode the H.264 video.

Different browsers and devices support the two codec types differently. The following table lists the codec support of different browsers:

Set the channel profile

The channel profile is a configuration that Agora uses to apply optimized algorithms for different real-time scenarios. Agora Web SDK supports two channel profiles: "rtc" (communication profile) and "live" (live streaming profile).

Communication profile

The communication profile applies to scenarios where all users in the channel often need to communicate with each other, but the total number of users is not too large, such as team meetings and online chats.

Live streaming profile

The live streaming profile applies to scenarios where the channel has few publishers but many subscribers. In this profile, the SDK defines two user roles: the audience and the host. The host can both send and receive audio and video, but the audience can only receive. You can set the role parameter of createClient to specify the user role, and call setClientRole to dynamically change the user role.

Join a channel

After creating the AgoraRTCClient object, call AgoraRTCClient.join to join a channel.

Note the setting of the fourth parameter uid of the join method. If no value is assigned, Agora automatically assigns a unique number ID for the local user. You can also specify a number user ID.

// Automatically assign a number user ID.
const uid = await client.join("APPID", "CHANNEL", "TOKEN");

// Specify a number user ID.
await client.join("APPID", "CHANNEL", "TOKEN", 393939);

Leave the channel

Call AgoraRTCClient.leave to leave the channel. You can call this method at any time, including when the user is joining a channel or reconnecting. After calling leave, the SDK immediately destroys objects related to the current channel, including subscribed remote user objects, remote track objects, and objects that save connection states. To join the channel again, call join after you call leave.

await client.leave();

Connection states in the channel

See Channel Connection.

Error handling

When joining a channel, the SDK may throw the following errors due to improper use of the SDK or network abnormalities:

• INVALID_PARAMS: The parameters are incorrect, for example, an invalid token is provided.
• INVALID_OPERATION: An incorrect operation. This error is usually caused by joining a channel repeatedly. Ensure that you call leave before joining a channel again.
• OPERATION_ABORTED: The joining is aborted, which means that leave is called before the method call of join succeeds.
• UNEXPECTED_RESPONSE: The Agora server returns an unexpected response, usually because the App ID or token authentication fails. For example, you have enabled the App Certificate but do not pass a token in join.
• UID_CONFLICT: Multiple AgoraRTCClient objects use the same user ID.