[Home](./index.md) > [@firebase/auth](./auth.md) > [RecaptchaVerifier](./auth.recaptchaverifier.md) > [(constructor)](./auth.recaptchaverifier._constructor_.md) ## RecaptchaVerifier.(constructor) Constructs a new instance of the `RecaptchaVerifier` class Signature: ```typescript constructor(containerOrId: HTMLElement | string, parameters: Parameters, authExtern: Auth); ``` ## Parameters | Parameter | Type | Description | | --- | --- | --- | | containerOrId | HTMLElement \| string | The reCAPTCHA container parameter. | | parameters | Parameters | The optional reCAPTCHA parameters. | | authExtern | [Auth](./auth.auth.md) | The corresponding Firebase Auth instance. | ## Remarks If none is provided, the default Firebase Auth instance is used. A Firebase Auth instance must be initialized with an API key, otherwise an error will be thrown.