How to get result from javascript code run by runJavaScript in QtWebengine?

[qtcentre2019]

How can I get the result from javascript run by runJavaScript in QtWebengine?

I want to get result from the js run by runJavaScript. The result is formed after some time in js, but since js returns immediately, I can not get the mature result. How can I modify the js code or the C++ code to get the mature result? I know I can use QWebChannel to notify C++ of the mature result at appropriate time but that is a little complex. Can I delay the return time of js code so it can return with the matured result?

C++:

page()->runJavaScript(js,[this](const QVariant &v) {
        qDebug()<<v.toString();
}

page()->runJavaScript(js,[this](const QVariant &v) {
        qDebug()<<v.toString();
}

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js:

var result="immature result";
function fun()
{
    result="mature result";
}
setTimeout(fun,2000);
result;

var result="immature result";
function fun()
{
    result="mature result";
}
setTimeout(fun,2000);
result;

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