I am looking for a way to get the collection size of a mongoDB collection in nodeJS including the indexes.

Is there any way to calculate the size of a collection (preferebly after a .find() statement to get the size of a part of the collection) in nodejs?

I can only run the db.stats() which returns the stats of the whole database, as soon as I try running it on a collection: db.collection('Documents') I get an error.
Running db.collection('Documents').totalSize() only gives an error saying it is not defined.
I have also tried the bson package, which only returns the size of files themselves, not the indexes:

const documentCollection = await db.collection('Documents').find({owner: userId}).toArray()
const size = BSON.calculateObjectSize(documentCollection)