Question

MongoDB converts the JavaScript objects emitted by the map function to ________ objects.

(a) BSON

(b) JSON

(c) Javascript

(d) None of the mentioned

I have been asked this question during an interview.

This intriguing question originated from Map-Reduce and Sharded Collections in division Aggregation Concepts and Aggregation Mechanics of MongoDB

Answer 1

Right answer is (a) BSON

For explanation I would say: These BSON objects are then converted back to JavaScript objects when calling the reduce function.