Before rendering, retrieve the hostname from the request being
        responded to and generate an URL which will serve as the root for
        all JavaScript modules to be loaded.

def beforeRender(self, ctx):
        """
        Before rendering, retrieve the hostname from the request being
        responded to and generate an URL which will serve as the root for
        all JavaScript modules to be loaded.
        """
        request = IRequest(ctx)
        root = self.webSite.rootURL(request)
        self._moduleRoot = root.child('__jsmodule__')