如何在JS中声明变量以通过getMember（）JavaFX获得它

Question

我在JavaFx应用程序中有一个控制器，该控制器可通过WebView加载Web内容。我想访问JavaScript中声明的变量。所以我有一个问题，因为我是JS的新手。如何在JavaScript中声明变量以通过JSObject类中的getMember（）方法访问它？控制器如下所示：

public class MainController implements Initializable {

    @FXML
    public WebView webView;

    @FXML
    private ListView<String> listOfInterest;

    //Variables to load map page
    private WebEngine webEngine;

    /*MenuBar methods*/
    @Function
    public void closeApplication() {
        Optional<ButtonType> confirmationResult = Dialog.closeApplicationConfirmation();
        if (confirmationResult.get() == ButtonType.OK) {
            Platform.exit();
        }
    }

    @Function
    public void openReport() {
        try {
            AnchorPane anchorPane = UtilsConnection.getFXML("/FXML/ReportWindow.fxml");
            Scene scene = new Scene(anchorPane);
            Stage stage = new Stage();
            stage.setScene(scene);
            stage.setTitle(UtilsConnection.getBundles().getString("title.rep"));
            stage.getIcons().add(new Image("images/logo.png"));
            stage.setResizable(false);
            stage.show();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    @Function
    public void openAbout() {
        Dialog.informationAlert(UtilsConnection.getBundles().getString("textAbout.app")
                ,UtilsConnection.getBundles().getString("headerAbout.app")
                ,UtilsConnection.getBundles().getString("aboutTitle.app"));
    }


    @Override
    public void initialize(URL location, ResourceBundle resources) {

        //Loading map through HTML file
        try {
            URL url = this.getClass().getResource("/html/mainMap.html");
            webEngine = webView.getEngine();
            webEngine.setJavaScriptEnabled(true);
            webEngine.getLoadWorker().stateProperty().addListener(((observable, oldValue, newState) -> {
                if(newState == Worker.State.SUCCEEDED){
                    JSObject fromJS = (JSObject) webEngine.getDocument();
                    String value = (String) fromJS.getMember("toJava");
                    System.out.println(value);
                }
            }));
            webEngine.load(url.toString());
        } catch (Exception e) {
            Dialog.error(UtilsConnection.getBundles().getString("error.map"));
        }