Initialization

Configure and initialize the CometChat JavaScript SDK with your App ID and settings.

The init() method initializes the SDK and must be called before any other CometChat method. Call it once at app startup, typically in your entry file (index.js, main.js, or App.js).

Basic Initialization

TypeScript

let appID: string = "APP_ID";
let region: string = "APP_REGION";

let appSetting: CometChat.AppSettings = new CometChat.AppSettingsBuilder()
  .subscribePresenceForAllUsers()
  .setRegion(region)
  .autoEstablishSocketConnection(true)
  .build();

CometChat.init(appID, appSetting).then(
  (initialized: boolean) => {
    console.log("Initialization completed successfully", initialized);
  },
  (error: CometChat.CometChatException) => {
    console.log("Initialization failed with error:", error);
  }
);

JavaScript

let appID = "APP_ID";
let region = "APP_REGION";

let appSetting = new CometChat.AppSettingsBuilder()
  .subscribePresenceForAllUsers()
  .setRegion(region)
  .autoEstablishSocketConnection(true)
  .build();

CometChat.init(appID, appSetting).then(
  () => {
    console.log("Initialization completed successfully");
  },
  (error) => {
    console.log("Initialization failed with error:", error);
  }
);

Alternatively, you can use the async/await syntax:

let appID = "APP_ID";
let region = "APP_REGION";

let appSetting = new CometChat.AppSettingsBuilder()
  .subscribePresenceForAllUsers()
  .setRegion(region)
  .autoEstablishSocketConnection(true)
  .build();

try {
  await CometChat.init(appID, appSetting);
  console.log("Initialization completed successfully");
} catch (error) {
  console.log("Initialization failed with error:", error);
}

Replace APP_ID with your CometChat App ID and APP_REGION with your Region from the Dashboard.

CometChat.init() must be called before any other SDK method. Calling login(), sendMessage(), or registering listeners before init() will fail.

Parameters

Parameter	Type	Description
appID	string	Your CometChat App ID
appSetting	AppSettings	Configuration object built with AppSettingsBuilder

AppSettings Options

Method	Description	Default
setRegion(region)	Region where your app was created (us, eu, in)	Required
subscribePresenceForAllUsers()	Subscribe to presence events for all users	—
subscribePresenceForRoles(roles)	Subscribe to presence for specific roles	—
subscribePresenceForFriends()	Subscribe to presence for friends only	—
autoEstablishSocketConnection(bool)	Let SDK manage WebSocket connections	true
overrideAdminHost(adminHost)	Custom admin URL (dedicated deployment)	—
overrideClientHost(clientHost)	Custom client URL (dedicated deployment)	—
setStorageMode(storageMode)	Local storage mode (CometChat.StorageMode.SESSION for session storage)	—

Presence Subscription

Choose how to subscribe to user presence (online/offline status):

// All users
new CometChat.AppSettingsBuilder()
  .subscribePresenceForAllUsers()
  .setRegion(region)
  .build();

// Specific roles
new CometChat.AppSettingsBuilder()
  .subscribePresenceForRoles(["admin", "moderator"])
  .setRegion(region)
  .build();

// Friends only
new CometChat.AppSettingsBuilder()
  .subscribePresenceForFriends()
  .setRegion(region)
  .build();

See User Presence for more details.

WebSocket Connection

By default, the SDK manages WebSocket connections automatically. To manage them manually:

let appSetting = new CometChat.AppSettingsBuilder()
  .setRegion(region)
  .autoEstablishSocketConnection(false)
  .build();

See Managing WebSocket Connections for manual control.

Session Storage

Use session storage instead of local storage (data clears when browser closes):

let appSetting = new CometChat.AppSettingsBuilder()
  .setRegion(region)
  .setStorageMode(CometChat.StorageMode.SESSION)
  .build();

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Next Steps

Authentication

Log in users with Auth Key or Auth Token

SSR Compatibility

Setup for Next.js, Nuxt, and Ionic