gistfile1.txt

static bool add (JSContext *cx, unsigned argc, jsval *vp){
        JS::CallArgs args = CallArgsFromVp(argc, vp);
        std::cout<<(args[0].toInt32()+args[1].toInt32());
        RootedFunction func(cx, JS_ValueToFunction(cx, args[2]));
        // JSFunction* function;
        JS::RootedValue rval(cx);
        JS::RootedObject global(cx, JS::CurrentGlobalOrNull(cx));
        JS_CallFunction(cx, global, &func, 0, nullptr, &rval);
        return true;
}