javaScriptWindowObjectCleared signal is not invoked while html page loaded in qwebview - qt

Question

I am new to QT. I have been trying to see the bridge between javascript and Qt Class.
What I did:
1) I have a button and connected clicked signal to on_pushButton_clicked, also I have qwebview instance.
In on_pushButton_clicked:
...
QUrl url = QUrl::fromLocalFile("C:\\whoami\\sd\\index.html");
QObject::connect(ui->webView->page()->mainFrame(), SIGNAL(javaScriptWindowObjectCleared()),
this, SLOT(addJSObject()));
ui->webView->page()->mainFrame()->load(QUrl(url));
....
and in addJSObject,
void MainWindow::addJSObject()
{
qDebug () <<"Inside addJSObject";
ui->webView->page()->mainFrame()->addToJavaScriptWindowObject(QString("mBridge"), m_bridge);
qDebug () <<"Nooo. I m not invoked..";
}
Problem:
It compiles without error, and html file is displayed in the qwebview, but addJSObject callback is not invoked.
Could someone help me in order to resolve this issue?.. I must have done some silly mistake. :(.

Answer 1

Make sure, that your MainWindow: 1) inherits QObject 2) has Q_OBJECT macro 3) has a slot addJSObject().
For example mainwindow.h:
class MainWindow : public QObject
{
Q_OBJECT
public:
MainWindow();
private slots:
void addJSObject();
};
If this is correct, you should be able to connect to addJSObject() without static QObject::connect(). Just use connect() when referring to this as signal target object.
One way to just check, that your signalling works is to try using QTimer timeout signal:
QTimer::singleShot(5000, this, SLOT(addJSObject()));