CDHtmlDialog 调用javascript

IHTMLDocument2* pDocument;
HRESULT hr = GetDHtmlDocument(&pDocument);
IHTMLWindow2* pWindow;
hr = pDocument->get_parentWindow(&pWindow);
VARIANT ret;
ret.vt = VT_EMPTY;

CComBSTR func=_T("getAlert()");
CComBSTR lang=_T("javascript");

//hr = pWindow->execScript( _T("getAlert()"), _T("javascript"), &ret);
// hr = pWindow->execScript( func, lang,&ret);

DISPID dispid;
DISPPARAMS dispparams;
memset(&dispparams, 0, sizeof dispparams);

dispparams.cArgs=1;
dispparams.rgvarg = new VARIANT[dispparams.cArgs];
CComBSTR fromMFC=_T("from mfc");
fromMFC.CopyTo(&dispparams.rgvarg[0].bstrVal);
dispparams.rgvarg[0].vt = VT_BSTR;

EXCEPINFO excepInfo;
memset(&excepInfo, 0, sizeof excepInfo);
CComVariant vaResult;
UINT nArgErr = (UINT)-1;

CComBSTR szMember = _T("getAlert");

hr = pWindow->GetIDsOfNames(IID_NULL, &szMember,1,LOCALE_SYSTEM_DEFAULT,&dispid);
hr = pWindow->Invoke(dispid, IID_NULL, 0, DISPATCH_METHOD, &dispparams, &vaResult, &excepInfo,&nArgErr);

MessageBox(vaResult.bstrVal);

pDocument->Release();
pWindow->Release();