veritatisdoloremque/docs-exp/auth-types.multifactorassertion.md

Monorepo for the Firebase JavaScript SDK

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[Home](./index.md) &gt; [@firebase/auth-types](./auth-types.md) &gt; [MultiFactorAssertion](./auth-types.multifactorassertion.md)

## MultiFactorAssertion interface

The base class for asserting ownership of a second factor.

<b>Signature:</b>

```typescript
export interface MultiFactorAssertion 
```

## Remarks

This is used to facilitate enrollment of a second factor on an existing user or sign-in of a user who already verified the first factor.

## Properties

|  Property | Type | Description |
|  --- | --- | --- |
|  [factorId](./auth-types.multifactorassertion.factorid.md) | [FactorId](./auth-types.factorid.md) | The identifier of the second factor. |