How do I get the return value of IHTMLWindow2::execScript?

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I've been trying to get the return value of a Javascript function from within C++ using IHTMLWindow2::execScript however, it never seems to work. The following is an example of what I am trying to perform.

C++ Code:

C++

CComPtr<IHTMLWindow2> win;
doc2->get_parentWindow( &win);
CComVariant empty;

CComBSTR fullScript = L"function testFunction(){";
fullScript += L"return 2254;";
fullScript += L"}";
fullScript += L"testFunction();";

win->execScript(fullScript.m_str, L"JAVASCRIPT", &empty);

The CComVariant empty is always empty. All the examples out there use INVOKE to call a javascript function which is already embedded within the HTML page. In my case, I need to get the return value of a Javascript function on the fly that isn't embedded within my HTML page.

Any ideas? Thanks in advance!

Posted 19-Jan-15 2:20am

Daroosh

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2 solutions

Solution 1

The article JavaScript-call-from-C enlights how to work with javscript from C++. But Microsoft says since IE 11: "Starting with IE11, use eval"...

Posted 19-Jan-15 3:16am

KarstenK

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Daroosh 19-Jan-15 10:04am

Thanks a lot KarstenK however, this article and almost all the other articles describe how to call JS functions that are already embedded within the page's HTML source. I don't need that, I need to call JS functions on the fly that aren't embedded within the HTML source.

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Daroosh · Accepted Answer · 2015-01-19T05:03:00

After searching around for a couple of hours, I managed to make it run as required. The following is a snippet for how to make it work (runs within DOCUMENTCOMPLETE):

C++

// Get IHTMLWindow
CComPtr<ihtmlwindow2> win;
doc2->get_parentWindow( &win);

if (win == NULL) return E_FAIL;
			
// Get IHTMLWindow dispatch
CComDispatchDriver dispWindow;
win->QueryInterface(&dispWindow);
			
if (dispWindow == NULL) return E_FAIL;
			
// Define JAVAScript
CComBSTR fullScript = L"function testFunction(){";
fullScript += L"alert('JS function called!')";
fullScript += L"return  true;";
fullScript += L"}testFunction();";
CComVariant script(fullScript.m_str);
CComVariant result;
			
// Execute JavaSctript
dispWindow.Invoke1(L"eval", &script, &result);
			
result.ChangeType(VT_BSTR);
			
// Print Result
LOG(L"%s", result.bstrVal);
</ihtmlwindow2>