MongoDB Extended JSON

JSON can only represent a subset of the types supported by BSON. To preserve type information, MongoDB adds the following extensions to the JSON format:

Strict mode. Strict mode representations of BSON types conform to the JSON RFC. Any JSON parser can parse these strict mode representations as key/value pairs; however, only the MongoDB’s internal JSON parser also recognizes the type information conveyed by the format.

mongo Shell mode. The MongoDB’s internal JSON parser and the mongo shell can parse this mode.