How to call a JavaScript funtion from C++ XPCOM object

[nk]

I have written a C++ XPCOM object. I would like to call a javascript 
function from this object which is defined in html page hosting XPCOM 
object.

In other words, I am looking for something equivalent to the following in IE
                                pIHTMLWindow->execScript(bstrScript,NULL,&vtResult);

where bstrScript could have any JavaScript code.

-NK