<input type="text" id="input">
<script>
    const testAssertionMessageLongBase64 =
        "AKUBomJpZFhAKAitzuj+Tslzelf3/vZwIGtDQNgoKeFd5oEieYzhyzA65saf0tK2" +
        "w/mooa7tQtGgDdwZIjOhjcuZ0pQ1ajoE4GR0eXBlanB1YmxpYy1rZXkCWCVGzH+5" +
        "Z51VstuQkuHI2eXh0Ct1gPC0gSx3CWLh5I9a2AEAAABQA1hHMEUCIQCSFTuuBWgB" +
        "4/F0VB7DlUVM09IHPmxe1MzHUwRoCRZbCAIgGKov6xoAx2MEf6/6qNs8OutzhP2C" +
        "QoJ1L7Fe64G9uBcEpGJpZFggMIIBkzCCATigAwIBAjCCAZMwggE4oAMCAQIwggGT" +
        "MIJkaWNvbngoaHR0cHM6Ly9waWNzLmFjbWUuY29tLzAwL3AvYUJqampwcVBiLnBu" +
        "Z2RuYW1ldmpvaG5wc21pdGhAZXhhbXBsZS5jb21rZGlzcGxheU5hbWVtSm9obiBQ" +
        "LiBTbWl0aAUC";
    const testAssertionMessageBase64 =
        "AKMBomJpZFhAKAitzuj+Tslzelf3/vZwIGtDQNgoKeFd5oEieYzhyzA65saf0tK2" +
        "w/mooa7tQtGgDdwZIjOhjcuZ0pQ1ajoE4GR0eXBlanB1YmxpYy1rZXkCWCVGzH+5" +
        "Z51VstuQkuHI2eXh0Ct1gPC0gSx3CWLh5I9a2AEAAABQA1hHMEUCIQCSFTuuBWgB" +
        "4/F0VB7DlUVM09IHPmxe1MzHUwRoCRZbCAIgGKov6xoAx2MEf6/6qNs8OutzhP2C" +
        "QoJ1L7Fe64G9uBc=";
    if (window.internals) {
        internals.setMockWebAuthenticationConfiguration({ silentFailure: true, hid: { payloadBase64: [testAssertionMessageLongBase64, testAssertionMessageBase64] } });
        internals.withUserGesture(() => { input.focus(); });
    }

    function bytesToHexString(bytes)
    {
        if (!bytes)
            return null;

        bytes = new Uint8Array(bytes);
        var hexBytes = [];

        for (var i = 0; i < bytes.length; ++i) {
            var byteString = bytes[i].toString(16);
            if (byteString.length < 2)
                byteString = "0" + byteString;
            hexBytes.push(byteString);
        }

        return hexBytes.join("");
    }

    const options = {
        publicKey: {
            challenge: new Uint8Array(16),
            timeout: 100
        }
    };

    navigator.credentials.get(options).then(credential => {
        userHandle = bytesToHexString(credential.response.userHandle);
        // console.log("Succeeded!");
        window.webkit.messageHandlers.testHandler.postMessage("Succeeded!");
    }, error => {
        // console.log(error.message);
        window.webkit.messageHandlers.testHandler.postMessage(error.message);
    });
</script>