# - [firebase](https://firebase.google.com/docs/reference/node/firebase).
- [auth](https://firebase.google.com/docs/reference/node/firebase.auth).
- MultiFactorAssertion

The base class for asserting ownership of a second factor. 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.

## Index

### Properties

- [factorId](https://firebase.google.com/docs/reference/node/firebase.auth.multifactorassertion#factorid)

## Properties

### factorId

factorId: string The identifier of the second factor.