Based on MongoDB's BSON description, but implemented in a "best effort" fashion to make the output as close to native JSON as possible (so this is not Extended JSON exactly).
let myJSON = myBSON.toJSON()
let myBSON = myJSON.toBSON()
Currently not being updated until BSON 4.0 releases
Please create an issue with a description of your problem or open a pull request with a fix.
Joannis Orlandos - http://orlandos.nl