How to access child properties?

Question

Node.js

there is an object

{
            "comments": 0,
            "_id": "5e7a142125a650dfa132b984",
            "title": "dasdadasd",
            "description": "dasdasdadasdasdasd",
            "author": {
                "_id": "5e7a142125a650dfa132b985",
                "name": "Artem",
                "userId": "5e7a0bea506a9edca2abaf6c"
            }
        }

I need to access in this code userId:
1
Posts.find({ author: { userId: user._id } });

2
Posts.find({ 'author.userId': user._id });

But this implementation does not work

Answer 1

user["id"]