Calling a Javascript API from an NPAPI DLL

Question

I'm writing an extension for Google Chrome that uses an NPAPI DLL. In the invoke method of the NPAPI DLL, I have inserted the following code to print a message to the javascript console:

char* message = "Hello from C++";

 // Get window object. NPObject* window = NULL; npnfuncs->getvalue(thisObj->npp, NPNVWindowNPObject, &window); // Get console object. NPVariant consoleVar; NPIdentifier id = npnfuncs->getstringidentifier("console"); npnfuncs->getproperty(thisObj->npp, window, id, &consoleVar); NPObject* console = NPVARIANT_TO_OBJECT(consoleVar); // Get the debug object. id = npnfuncs->getstringidentifier("log"); //console. // Invoke the call with the message! NPVariant type; STRINGZ_TO_NPVARIANT(message, type); NPVariant args[] = { type }; NPVariant voidResponse; bool didRun = npnfuncs->invoke(thisObj->npp, console, id, args, sizeof(args) / sizeof(args[0]), &voidResponse); if (!didRun) assert(false); // Cleanup all allocated objects, otherwise, reference count and // memory leaks will happen. npnfuncs->releaseobject(window); npnfuncs->releasevariantvalue(&consoleVar); npnfuncs->releasevariantvalue(&voidResponse); 

Nothing is getting printed to the console, and neither is the assert failing. I'm not sure if there's a problem with my console.log statements as they don't print anything even when I use them with other javascript files. I want to use a statement like alert("Hello, world!") instead for the moment. I could modify my code to call functions of the form xy() , but I don't understand how should I go about displaying an alert box. I used the tutorial at the following link . What should I do to display an alert box, called from the NPAPI DLL?

Edit: I am able to call the alert using it's window.alert("") form ( XY() form ), but this doesn't still solve my problem. I still don't understand how should I call a function of type X() directly from the NPAPI.

Answer 1

Found it! I couldn't find a specific method to call a function of type X() . Instead, I was able to call it as window.X() , by placing the definition of function X() in the background.html page of the extension. So, if I created a function function myAlert(message){alert(message);} and placed it in background.html, I could make a call to window.myAlert(argument) from the NPAPI, and the above function would get called.