Passkey Login: Immediate Mode

async function tryImmediateSignIn() {
  const capabilities = await PublicKeyCredential.getClientCapabilities();
  if (!capabilities.immediateGet) return showLoginForm();

  try {
    const credential = await navigator.credentials.get({
      password: true, // also offer passwords saved in Google Password Manager
      publicKey: {
        challenge: serverGeneratedChallenge,
        rpId: 'example.com',
        // allowCredentials must be omitted or empty
      },
      uiMode: 'immediate',
    });
    return completeSignIn(credential);
  } catch (error) {
    if (error.name === 'NotAllowedError') return showLoginForm();
    throw error;
  }
}