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app-check package

The Firebase App Check Web SDK.

Firebase App Check does not work in a Node.js environment using ReCaptchaV3Provider or ReCaptchaEnterpriseProvider, but can be used in Node.js if you use CustomProvider and write your own attestation method.

Functions

Function	Description
<b>function(app, ...)</b>
initializeAppCheck(app, options)	Activate App Check for the given app. Can be called only once per app.
<b>function(appCheckInstance, ...)</b>
getLimitedUseToken(appCheckInstance)	Requests a Firebase App Check token. This method should be used only if you need to authorize requests to a non-Firebase backend.<!-- -->Returns limited-use tokens that are intended for use with your non-Firebase backend endpoints that are protected with <a href="https://firebase.google.com/docs/app-check/custom-resource-backend#replay-protection"> Replay Protection</a>. This method does not affect the token generation behavior of the #getAppCheckToken() method.
getToken(appCheckInstance, forceRefresh)	Get the current App Check token. If <code>forceRefresh</code> is false, this function first checks for a valid token in memory, then local persistence (IndexedDB). If not found, or if <code>forceRefresh</code> is true, it makes a request to the App Check endpoint for a fresh token. That request attaches to the most recent in-flight request if one is present.
onTokenChanged(appCheckInstance, observer)	Registers a listener to changes in the token state. There can be more than one listener registered at the same time for one or more App Check instances. The listeners call back on the UI thread whenever the current token associated with this App Check instance changes.
onTokenChanged(appCheckInstance, onNext, onError, onCompletion)	Registers a listener to changes in the token state. There can be more than one listener registered at the same time for one or more App Check instances. The listeners call back on the UI thread whenever the current token associated with this App Check instance changes.
setTokenAutoRefreshEnabled(appCheckInstance, isTokenAutoRefreshEnabled)	Set whether App Check will automatically refresh tokens as needed.

Classes

Class	Description
CustomProvider	Custom provider class.
ReCaptchaEnterpriseProvider	App Check provider that can obtain a reCAPTCHA Enterprise token and exchange it for an App Check token.
ReCaptchaV3Provider	App Check provider that can obtain a reCAPTCHA V3 token and exchange it for an App Check token.

Interfaces

Interface	Description
AppCheck	The Firebase App Check service interface.
AppCheckOptions	Options for App Check initialization.
AppCheckToken	The token returned from an App Check provider.
AppCheckTokenResult	Result returned by <code>getToken()</code>.
CustomProviderOptions	Options when creating a CustomProvider<!-- -->.

Type Aliases

Type Alias	Description
AppCheckTokenListener	A listener that is called whenever the App Check token changes.

function(app, ...)

initializeAppCheck(app, options) {:#initializeappcheck_5548dfc}

Activate App Check for the given app. Can be called only once per app.

Signature:

typescript

export declare function initializeAppCheck(app: FirebaseApp | undefined, options: AppCheckOptions): AppCheck;

Parameters

Parameter	Type	Description
app	FirebaseApp \| undefined	the FirebaseApp to activate App Check for
options	AppCheckOptions	App Check initialization options

Returns:

AppCheck

function(appCheckInstance, ...)

getLimitedUseToken(appCheckInstance) {:#getlimitedusetoken_53ef5e3}

Requests a Firebase App Check token. This method should be used only if you need to authorize requests to a non-Firebase backend.

Returns limited-use tokens that are intended for use with your non-Firebase backend endpoints that are protected with <a href="https://firebase.google.com/docs/app-check/custom-resource-backend#replay-protection"> Replay Protection</a>. This method does not affect the token generation behavior of the #getAppCheckToken() method.

Signature:

typescript

export declare function getLimitedUseToken(appCheckInstance: AppCheck): Promise<AppCheckTokenResult>;

Parameters

Parameter	Type	Description
appCheckInstance	AppCheck	The App Check service instance.

Returns:

Promise<AppCheckTokenResult>

The limited use token.

getToken(appCheckInstance, forceRefresh) {:#gettoken_39fc1b3}

Get the current App Check token. If forceRefresh is false, this function first checks for a valid token in memory, then local persistence (IndexedDB). If not found, or if forceRefresh is true, it makes a request to the App Check endpoint for a fresh token. That request attaches to the most recent in-flight request if one is present.

Signature:

typescript

export declare function getToken(appCheckInstance: AppCheck, forceRefresh?: boolean): Promise<AppCheckTokenResult>;

Parameters

Parameter	Type	Description
appCheckInstance	AppCheck	The App Check service instance.
forceRefresh	boolean	If true, will always try to fetch a fresh token. If false, will use a cached token if found in storage.

Returns:

Promise<AppCheckTokenResult>

onTokenChanged(appCheckInstance, observer) {:#ontokenchanged_9761e16}

Registers a listener to changes in the token state. There can be more than one listener registered at the same time for one or more App Check instances. The listeners call back on the UI thread whenever the current token associated with this App Check instance changes.

Signature:

typescript

export declare function onTokenChanged(appCheckInstance: AppCheck, observer: PartialObserver<AppCheckTokenResult>): Unsubscribe;

Parameters

Parameter	Type	Description
appCheckInstance	AppCheck	The App Check service instance.
observer	PartialObserver<!-- --><AppCheckTokenResult<!-- -->>	An object with <code>next</code>, <code>error</code>, and <code>complete</code> properties. <code>next</code> is called with an AppCheckTokenResult whenever the token changes. <code>error</code> is optional and is called if an error is thrown by the listener (the <code>next</code> function). <code>complete</code> is unused, as the token stream is unending.

Returns:

Unsubscribe

A function that unsubscribes this listener.

onTokenChanged(appCheckInstance, onNext, onError, onCompletion) {:#ontokenchanged_8ef80a7}

Signature:

typescript

export declare function onTokenChanged(appCheckInstance: AppCheck, onNext: (tokenResult: AppCheckTokenResult) => void, onError?: (error: Error) => void, onCompletion?: () => void): Unsubscribe;

Parameters

Parameter	Type	Description
appCheckInstance	AppCheck	The App Check service instance.
onNext	(tokenResult: AppCheckTokenResult<!-- -->) => void	When the token changes, this function is called with an AppCheckTokenResult<!-- -->.
onError	(error: Error) => void	Optional. Called if there is an error thrown by the listener (the <code>onNext</code> function).
onCompletion	() => void	Currently unused, as the token stream is unending.

Returns:

Unsubscribe

A function that unsubscribes this listener.

setTokenAutoRefreshEnabled(appCheckInstance, isTokenAutoRefreshEnabled) {:#settokenautorefreshenabled_057a76c}

Set whether App Check will automatically refresh tokens as needed.

Signature:

typescript

export declare function setTokenAutoRefreshEnabled(appCheckInstance: AppCheck, isTokenAutoRefreshEnabled: boolean): void;

Parameters

Parameter	Type	Description
appCheckInstance	AppCheck	The App Check service instance.
isTokenAutoRefreshEnabled	boolean	If true, the SDK automatically refreshes App Check tokens as needed. This overrides any value set during <code>initializeAppCheck()</code>.

Returns:

void

AppCheckTokenListener

A listener that is called whenever the App Check token changes.

Signature:

typescript

export type AppCheckTokenListener = (token: AppCheckTokenResult) => void;