test.js

window.addEventListener("documentViewerLoaded", function () {
    TXDocumentViewer.addEventListener("annotationsChanged", updateAnnotations);
});

function updateAnnotations() {

    if (_updating === true)
        return;

    var jsonAnnotations = TXDocumentViewer.annotations.export();

    // create sync object
    var collaborationSyncObject = {
        User: "Test",
        AnnotationJson: jsonAnnotations
    };

    // call signalr hub with sync object
    _connection.invoke("SetAnnotationSync",
        collaborationSyncObject).catch(function (err) {
            return console.error(err.toString());
        }
    );

}