@anjunar/scalajs-ui-webauthn

The browser-side WebAuthn and passkey API for Scala JS UI 1.0. It is independent of the UI component runtime and is the TypeScript counterpart of scalajs-ui-webauthn.

Installation

npm install @anjunar/scalajs-ui-webauthn

Registration and authentication

Use the JSON methods with the options returned by a relying-party backend. The module uses the browser's Level 3 JSON parser when available and has a strict Level 2 fallback for older browsers.

import { authenticateJson, registerJson } from "@anjunar/scalajs-ui-webauthn";

const registration = await registerJson(await fetch("/webauthn/register/options").then((r) => r.json()));
await fetch("/webauthn/register/verify", {
  method: "POST",
  body: JSON.stringify(registration),
  headers: { "content-type": "application/json" },
});

const authentication = await authenticateJson(await fetch("/webauthn/auth/options").then((r) => r.json()));

Already decoded browser dictionaries can be passed to register and authenticate. CredentialCreationSettings and CredentialRequestSettings carry an AbortSignal and mediation mode. All operations return native Promises; the *Promise names are provided as migration-friendly aliases for the Scala.js API.

Capabilities and credential synchronization

import {
  CredentialMediationRequirement,
  isAvailable,
  isConditionalMediationAvailable,
  authenticateJson,
} from "@anjunar/scalajs-ui-webauthn";

if (isAvailable() && await isConditionalMediationAvailable()) {
  await authenticateJson(optionsFromServer, {
    mediation: CredentialMediationRequirement.Conditional,
  });
}

clientCapabilities and the individual capability queries safely return empty or false outside a supporting browser. signalUnknownCredential, signalAllAcceptedCredentials, and signalCurrentUserDetails reject when the browser does not expose the corresponding WebAuthn Level 3 method.

JSON and Base64URL behavior

Credential responses contain base64url strings suitable for sending to a backend. Base64Url is public for application-specific binary fields. credentialToJson uses native PublicKeyCredential.toJSON() where available; the fallback recursively converts binary extension results to base64url.

WebAuthn ceremonies are only the browser boundary. Challenge generation and single use, origin and RP-ID validation, attestation policy, signature verification, sign-count handling, credential storage, and session establishment remain backend responsibilities.

API overview

• register, registerJson, authenticate, authenticateJson
• isSupported, isAvailable, and capability queries
• credential synchronization signal methods
• typed public-key option facades and WebAuthn value constants
• Base64Url, WebAuthnCodecs, RegistrationCredential, and AuthenticationCredential