PublicKeyCredentialCreationOptions

// some examples of COSE algorithms
const cose_alg_ECDSA_w_SHA256 = -7;
const cose_alg_ECDSA_w_SHA512 = -36;

var createCredentialOptions = {
    // Format of new credentials is publicKey
    publicKey: {
        // Relying Party
        rp: {
            name: "Example CORP",
            id: "login.example.com",
            icon: "https://login.example.com/login.ico"
        },
        // Cryptographic challenge from the server
        challenge: new Uint8Array(26),
        // User
        user: {
            id: new Uint8Array(16),
            name: "john.p.smith@example.com",
            displayName: "John P. Smith",
        },
        // Requested format of new keypair
        pubKeyCredParams: [{
            type: "public-key",
            alg: cose_alg_ECDSA_w_SHA256,
        }],
        // Timeout after 1 minute
        timeout: 60000,
        // Do not send the authenticator's origin attestation
        attestation: "none",
        extensions: {
          uvm: true,
          exts: true
        },
        // Filter out authenticators which are bound to the device
        authenticatorSelection:{
          authenticatorAttachment: "cross-platform",
          requireResidentKey: true,
          userVerification: "preferred"
        },
        // Exclude already existing credentials for the user
        excludeCredentials: [
          {
            type: "public-key",
            // the id for john.doe@example.com
            id  : new Uint8Array(26) /* this actually is given by the server */
          },
          {
            type: "public-key",
            // the id for john-doe@example.com
            id : new Uint8Array(26) /* another id */
          }
        ]
    }
};

// Create the new credential with the options above
navigator.credentials.create(createCredentialOptions)
  .then(function (newCredentialInfo) {
    var attestationResponse = newCredentialInfo.response;
    var clientExtensionsOutputs = newCredentialInfo.getClientExtensionsResults();

    // Send the response to the relying party server
    // it will verify the content and integrity before
    // creating a new credential

  }).catch(function (err) {
    // Deal with any error properly
    console.error(err);
  });;