[Home](./index.md) > [@firebase/auth](./auth.md) > [OperationType](./auth.operationtype.md) ## OperationType enum Enumeration of supported operation types. Signature: ```typescript export declare const enum OperationType ``` ## Enumeration Members | Member | Value | Description | | --- | --- | --- | | LINK | "link" | Operation involving linking an additional provider to an already signed-in user. | | REAUTHENTICATE | "reauthenticate" | Operation involving using a provider to reauthenticate an already signed-in user. | | SIGN\_IN | "signIn" | Operation involving signing in a user. |