我想我已经弄明白了。我最终做的是在我的C ++类中实现这样：

I think I've figured this out. What I ended up doing was implementing this in my C++ class like such:

class MyObject: public QObject
{

Q_OBJECT

public:
    Q_INVOKABLE void doSomething(quint64 x, QJSValue jsCallback)
    {
        x += 1;

        QJSValue val = jsCallback.engine()->newObject();
        val.setProperty("x", x);

        jsCallback.call(QJSValueList { val });
    }
};

然后我可以在我的回调中访问该值，如：

And then I can access the value in my callback like:

function myCallback(x){
    console.log("x=" + x.x);
}