Re: Extending Native javascript in dom

Not sure if this is in the lines of what you need.
But this is more or less how I execute javascript from C++ in Mozilla:

/** Convert a std::string in UTF8 to Mozilla UTF16 string */
//inline nsEmbedString
inline nsString
toAStringUTF16 (const std::string& sString )		///< UTF8 std::string to
convert
{
	return NS_ConvertUTF8toUTF16( sString.c_str() );
}


/** Convert a Mozilla UTF16 string (nsEmbedString) to a std::string in
UTF8 */
inline std::string
toStdStringUTF8 (const nsString& aString )		///< Mozilla UTF16 string
to convert
{
	return NS_ConvertUTF16toUTF8(aString).get();
}


bool executeJavascriptString(
	nsCOMPtr<nsIScriptContext> pIScriptContext,
        const std::string& sScript, 		///< [in]	String with script to
execute
	std::string& sScriptReturnValue ) 	///< [out]	Return value of script
(if any)
{
	nsIPrincipal* thePrincipal = nsnull;
	nsString script= toAStringUTF16( sScript );
	PRBool bUndefined;
	nsString sReturnValue;
	nsresult rv = pIScriptContext->EvaluateString(
		script,
//		NS_LITERAL_STRING("bob();"),
		nsnull,	thePrincipal, "", 1,
		JSVERSION_DEFAULT,
//		JSVERSION_1_8,
		&sReturnValue, &bUndefined );

	sScriptReturnValue 	= toStdStringUTF8( sReturnValue );
	return !static_cast<bool>(bUndefined != 0);
}


/// Call the JS evaluate function

nsCOMPtr <nsIDOMWindow>  piMyDOMWindow;  // =  initialize to you dom
window
nsCOMPtr<nsIScriptGlobalObject>
pIScriptGlobalObject( do_GetInterface(piMyDOMWindow) );
nsCOMPtr<nsIScriptContext> pIScriptContext ( pIScriptGlobalObject-
>GetContext() );

std::string sRetVal;

executeJavascriptString (pIScriptContext, "alert('hey!');",
sRetVal );