The userHandle read-only property of the AuthenticatorAssertionResponse interface is an ArrayBuffer object providing an opaque identifier for the given user. Such an identifier can be used by the relying party's server to link the user account with its corresponding credentials and other data.

This value is specified as user.id in the options passed to the originating navigator.credentials.create() call.

An ArrayBuffer object representing an identifier for the current user. This is not intended to be human-readable. The relying party should make sure that the user.id passed into the originating create() call does not contain any personally identifying information (for example user name, email, or phone number).

For navigator.credentials.create() calls made with a non-empty allowCredentials properties, the returned userHandle may be null.

See User login using the WebAuthn API for a detailed example.

• CredentialsContainer.create() that sets the value of this property