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Version: v4


This guide demonstrates how to add chat to a Javascript application using CometChat. Before you begin, we strongly recommend you read the Key Concepts guide.

I want to explore a sample app (includes UI)

Open the app folder in your favorite code editor and follow the steps mentioned in the file.

React Sample App

Angular Sample App

Vue Sample App

Get your Application Keys

Signup for CometChat and then:

  1. Create a new app
  2. Head over to the API & Auth Keys section and note the Auth Key, App ID & Region

Add the CometChat Dependency


  npm install @cometchat/chat-sdk-javascript@latest --save

Then, import the CometChat object wherever you want to use CometChat.

  import { CometChat } from "@cometchat/chat-sdk-javascript";

HTML (via CDN)

Include the CometChat Javascript library in your HTML code


Server Side Rendering (SSR) Compatibility

You can use CometChat with SSR frameworks such as Next.js or NuxtJS by importing it dynamically on the client side.


You need to import the CometChat SDK dynamically in the useEffect React Hook or componentDidMount() lifecycle method.

import React from "react";
import Chat from "./Chat";

export default function Home() {
let [libraryImported, setLibraryImported] = React.useState(false);

React.useEffect(() => {
window.CometChat = require("@cometchat/chat-sdk-javascript").CometChat;

return libraryImported ? <Chat /> : <p>Loading....</p>;


You need to import the CometChat SDK dynamically in the mounted lifecycle hook.

<div v-if="libraryImported">
<div v-else>Loading....</div>

export default {
name: "Index",
components: {
'chat': () => import('./chat')
data() {
libraryImported: false
mounted() {
window.CometChat = require('@cometchat/chat-sdk-javascript').CometChat;
this.libraryImported = true;

Initialize CometChat

The init() method initializes the settings required for CometChat. The init() method takes the below parameters:

  1. appID - Your CometChat App ID
  2. appSettings - An object of the AppSettings class can be created using the AppSettingsBuilder class. The region field is mandatory and can be set using the setRegion() method.

The AppSettings class allows you to configure two settings:

  • Region: The region where your app was created.
  • Presence Subscription: Represents the subscription type for user presence (real-time online/offline status)
  • autoEstablishSocketConnection(boolean value): This property takes a boolean value which when set to true informs the SDK to manage the web-socket connection internally. If set to false, it informs the SDK that the web-socket connection will be managed manually. The default value for this parameter is true. For more information on this, please check the Managing Web-Socket connections manually section. The default value for this property is true.
  • overrideAdminHost(adminHost: string): This method takes the admin URL as input and uses this admin URL instead of the default admin URL. This can be used in case of dedicated deployment of CometChat.
  • overrideClientHost(clientHost: string): This method takes the client URL as input and uses this client URL instead of the default client URL. This can be used in case of dedicated deployment of CometChat.

You need to call init() before calling any other method from CometChat. We suggest you call the init() method on app startup, preferably in the index.js file.

let appID = "APP_ID";
let region = "APP_REGION";
let appSetting = new CometChat.AppSettingsBuilder()
CometChat.init(appID, appSetting).then(
() => {
console.log("Initialization completed successfully");
(error) => {
console.log("Initialization failed with error:", error);

Make sure you replace the APP_ID with your CometChat App ID and APP_REGION with your App Region in the above code.

Register and Login your user

Once initialization is successful, you will need to create a user. To create users on the fly, you can use the createUser() method. This method takes a User object and the Auth Key as input parameters and returns the created User object if the request is successful.

let authKey = "AUTH_KEY";
var UID = "user1";
var name = "Kevin";

var user = new CometChat.User(UID);


CometChat.createUser(user, authKey).then(
(user) => {
console.log("user created", user);
(error) => {
console.log("error", error);

Make sure that UID and name are specified as these are mandatory fields to create a user.

Once you have created the user successfully, you will need to log the user into CometChat using the login() method.

We recommend you call the CometChat login() method once your user logs into your app. The login() method needs to be called only once.


This straightforward authentication method is ideal for proof-of-concept (POC) development or during the early stages of application development. For production environments, however, we strongly recommend using an Auth Token instead of an Auth Key to ensure enhanced security.

var authKey = "AUTH_KEY";

(user) => {
if (!user) {
CometChat.login(UID, authKey).then(
(user) => {
console.log("Login Successful:", { user });
(error) => {
console.log("Login failed with exception:", { error });
(error) => {
console.log("Some Error Occured", { error });

Make sure you replace the AUTH_KEY with your CometChat AuthKey in the above code.

Sample Users

We have set up 5 users for testing having UIDs: SUPERHERO1, SUPERHERO2, SUPERHERO3, SUPERHERO4 and SUPERHERO5.

The login() method returns the User object on Promise resolved containing all the information of the logged-in user.


UID can be alphanumeric with an underscore and hyphen. Spaces, punctuation and other special characters are not allowed.

Integrate our UI Kits

  • Please refer to the section to integrate React UI Kit into your website.
  • Please refer to the section to integrate Angular UI Kit into your website.
  • Please refer to the section to integrate Vue UI Kit into your website.

Integrate our Chat Widget

  • Please refer to the section to integrate Chat Widget into your Website.