When you need to call the javascript function, is that as a result of javascript call to your addon? (ie. is there some other javascript on the stack?)

Hi @fholzer thank you for answering. No unfortunately I do not have access to the CallbackInfo.
We are mostly talking about system events like tracking the mouse movement so the call is going to be made by pure C++ code.

I think you'll probably need to use ThreadSafeFunction

When talking about javascript calls from additional threads, that doesn't necessarily mean threads that you directly start yourself. Could also be threads started by some other library your addon uses.

If you're calling from a non-N-API callback into JS on the same thread as JS, you can use MakeCallback.

If you're calling from a non-N-API callback into JS from a different thread, you can convert the Napi::Function you wish to call to a ThreadSafeFunction and call that from any thread.

Thank you @fholzer and @gabrielschulhof. I believe MakeCallback will do. I see from the docs that I need to pass the this (as Napi Value) representing the object but I am not sure how would I obtain it in this case.

I have a class that inherits from EventEmitter similarly to this example. I can see that in there the This is obtained through the CallbackInfo but again I am not going to have that

@simoneperelli do you need to have a This? If you have a FunctionReference you can call MakeCallback with Napi::Env::Undefined() as your This.

... and if you need to have a This you can create a reference to it and pass it along to wherever you call MakeCallback.

Thank you @gabrielschulhof will give it a try

@simoneperelli hopefully my suggestion worked for you. If it did not, and you believe we need to change node-addon-api or add something to it to better support your use case, please re-open this issue!

@gabrielschulhof Thank you !