useSignOut hook

useSignOut hook is used to sign out currently signed-in user. A very simple example would be:

const { dispatch } = useSignOut(auth);
await dispatch();

Warning

useSignOut is lazy by default and will not do anything until you use dispatch function.

You can also get the state¹ of sign-out process.

const { state, dispatch } = useSignOut(auth);
await dispatch();
// `state` is "ready" | "loading" | "anonymous"

Warning

useSignOut automatically listens to authentication state and will be "anonymous" if the user is anonymous. In "anonymous" state, dispatch will simply do nothing even if it is invoked.

In case of an error occurs, you can handle it by providing a function for onError:

const onError = (error: Error) => {
  // do something with error
}

const { dispatch } = useSignOut(auth, { onError });
await dispatch();

On Anonymity

In Firebase, there are two types of anonymity: Firebase-handled anonymous users (which are stored in Firebase and seen as real users) and real anonymous users (which are essentially null users).

useSignOut considers both cases as anonymous and behaves accordingly. So, in a case where user is Firebase-handled or really anonymous, useSignOut will have "anonymous" state. If, for a reason, this behavior is not desirable for you, you can use onlyRealAnon parameter on useSignOut hook. To see both cases, check this code:

const onlyRealAnon = true;

// User is really anonymous
const { state } = useSignOut(auth); // state: "anonymous"
const { state } = useSignOut(auth, { onlyRealAnon }); // state: "anonymous"

// User is anonymous in Firebase Auth records
const { state } = useSignOut(auth); // state: "anonymous"
const { state } = useSignOut(auth, { onlyRealAnon }); // state: "ready"

Input Parameters

Input parameters for useSignOut hook is as follows:

Name	Type	Description	Required	Default Value
auth	firebase/auth/Auth	Reference to the Firebase Auth service instance.	✅	-
options	Object	Options for the process.	❌	See below.
options.onError	(error: Error) => void	A function to handle errors.	❌	Throws error.
options.onlyRealAnon	boolean	Consider the user anonymous only if they are null.	❌	false (which also considers Firebase-handled anonymous users)

Return Type

useSignOut hook returns an object with properties as below:

Name	Type	Description
state	"ready" | "loading" | "anonymous"1	The state of sign-out process.
dispatch	() => Promise<void>	A callback to start sign-out process.

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1. You can consider "anonymous" state as logically done. ↩↩