> ## Documentation Index
> Fetch the complete documentation index at: https://cometchat-22654f5b-feature-react-native-sdk-quotedmessage-a.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Authentication

## Create User

Before you log in a user, you must add the user to CometChat.

1. **For proof of concept/MVPs**: Create the user using the [CometChat Dashboard](https://app.cometchat.com).
2. **For production apps**: Use the CometChat [Create User API](https://api-explorer.cometchat.com/reference/creates-user) to create the user when your user signs up in your app.

<Note>
  We have setup 5 users for testing having UIDs: `cometchat-uid-1`, `cometchat-uid-2`, `cometchat-uid-3`, `cometchat-uid-4` and `cometchat-uid-5`.
</Note>

Once initialization is successful, 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.

<Warning>
  The CometChat SDK maintains the session of the logged-in user within the SDK. Thus you do not need to call the login method for every session. You can use the CometChat.getLoggedinUser() method to check if there is any existing session in the SDK. This method should return the details of the logged-in user. If this method returns null, it implies there is no session present within the SDK and you need to log the user into CometChat.
</Warning>

## Login using Auth Key

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 [AuthToken](#login-using-auth-token) instead of an Auth Key to ensure enhanced security.

<Tabs>
  <Tab title="JavaScript">
    ```js theme={null}
    var UID = "UID";
    var authKey = "AUTH_KEY";

    CometChat.getLoggedinUser().then(
      (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("Something went wrong", error);
      }
    );
    ```
  </Tab>

  <Tab title="TypeScript">
    ```typescript theme={null}
    var UID: string = "cometchat-uid-1",
      authKey: string = "AUTH_KEY";

    CometChat.getLoggedinUser().then(
      (user: CometChat.User) => {
        if (!user) {
          CometChat.login(UID, authKey).then(
            (user: CometChat.User) => {
              console.log("Login Successful:", { user });
            },
            (error: CometChat.CometChatException) => {
              console.log("Login failed with exception:", { error });
            }
          );
        }
      },
      (error: CometChat.CometChatException) => {
        console.log("Some Error Occured", { error });
      }
    );
    ```
  </Tab>
</Tabs>

| Parameters | Description                                      |
| ---------- | ------------------------------------------------ |
| UID        | The UID of the user that you would like to login |
| authKey    | CometChat Auth Key                               |

After the user logs in, their information is returned in the `User` object on `Promise` resolved.

## Login using Auth Token

This advanced authentication procedure does not use the Auth Key directly in your client code thus ensuring safety.

1. [Create a User](https://api-explorer.cometchat.com/reference/creates-user) via the CometChat API when the user signs up in your app.
2. [Create an Auth Token](https://api-explorer.cometchat.com/reference/create-authtoken) via the CometChat API for the new user and save the token in your database.
3. Load the Auth Token in your client and pass it to the `login()` method.

<Tabs>
  <Tab title="JavaScript">
    ```js theme={null}
    var authToken = "AUTH_TOKEN";

    CometChat.getLoggedinUser().then(
      (user) => {
        if (!user) {
          CometChat.login(authToken).then(
            (user) => {
              console.log("Login Successful:", { user });
            },
            (error) => {
              console.log("Login failed with exception:", { error });
            }
          );
        }
      },
      (error) => {
        console.log("Something went wrong", error);
      }
    );
    ```
  </Tab>

  <Tab title="TypeScript">
    ```typescript theme={null}
    var authToken: string = "AUTH_TOKEN";

    CometChat.getLoggedinUser().then(
      (user: CometChat.User) => {
        if (!user) {
          CometChat.login(authToken).then(
            (user: CometChat.User) => {
              console.log("Login Successful:", { user });
            },
            (error: CometChat.CometChatException) => {
              console.log("Login failed with exception:", { error });
            }
          );
        }
      },
      (error: CometChat.CometChatException) => {
        console.log("Some Error Occured", { error });
      }
    );
    ```
  </Tab>
</Tabs>

| Parameter | Description                                    |
| --------- | ---------------------------------------------- |
| authToken | Auth Token of the user you would like to login |

After the user logs in, their information is returned in the `User` object on the `Promise` resolved.

## Logout

You can use the `logout()` method to log out the user from CometChat. We suggest you call this method once your user has been successfully logged out from your app.

<Tabs>
  <Tab title="JavaScript">
    ```js theme={null}
    CometChat.logout().then(
      () => {
        console.log("Logout completed successfully");
      },
      (error) => {
        console.log("Logout failed with exception:", { error });
      }
    );
    ```
  </Tab>

  <Tab title="TypeScript">
    ```typescript theme={null}
    CometChat.logout().then(
      (loggedOut: Object) => {
        console.log("Logout completed successfully");
      },
      (error: CometChat.CometChatException) => {
        console.log("Logout failed with exception:", { error });
      }
    );
    ```
  </Tab>
</Tabs>