Typescript error when trying to use an async function for signInSuccessWithAuthResult callback

[emwadde]

[REQUIRED] Describe your environment

• Operating System version: Ubuntu 22.04
• Browser version: Chrome 120.0.6099.62 (Official Build) beta (64-bit)
• Firebase UI version: 6.1.0
• Firebase SDK version: 10.7

[REQUIRED] Describe the problem

The interface for signInSuccessWithAuthResult callback currently is set to boolean at line 26 of types/index.d.ts.
As a result, typescript throws: Type 'Promise' is not assignable to type 'boolean' if the callback function is an async function.

Steps to reproduce:

set the uiConfig.callbacks.signInSuccessWithAuthResult to an async function

Relevant Code:

/**
 * @param  {import('firebase/auth').UserCredential} authResult
 * */
const signInSuccessCallback = async (authResult) => {
    const token = await authResult.user.getIdToken()
    console.log(token)
    return true
};

/**@type {import('firebaseui').auth.Config}*/
var uiConfig = {
    callbacks: {
        signInSuccessWithAuthResult: signInSuccessCallback
    },
    signInOptions: [{
        provider: GoogleAuthProvider.PROVIDER_ID,
        customParameters: {
            prompt: 'select_account'
        }
    }],
    signInFlow: 'popup',
    tosUrl: '/tos',
    privacyPolicyUrl: '/tos'
}

Workaround/Fix:

The issue is resolved by updating the Callback interface to include Promise<boolean> as a type for signInSuccessWithAuthResult

interface Callbacks {
  signInSuccessWithAuthResult?(
    // tslint:disable-next-line:no-any firebase dependency not available.
    authResult: any,
    redirectUrl?: string
  ): Promise<boolean>|boolean;  
  signInFailure?(error: firebaseui.auth.AuthUIError): Promise<void>|void;
  uiShown?(): void;
}

[jhuleatt]

Hi @emwadde, the types in types/index.d.ts are correct in this case - FirebaseUI doesn't expect a function that returns a promise that resolves to a boolean, it expects a function that returns a boolean (docs).

This would be a breaking change in FirebaseUI, so I'll leave it open as a feature request. If you'd like to provide more context on your use case (seems like you might be trying to get the JWT for a custom auth integration?), or if others would like to chime in, it would give us a better idea about whether we should prioritize this change.