How to store the additional properties in the user's Mongo document?

[cool]

In my case, they are the latitude and longitude of a user. What code do I need to write in my client-side JS and backend controller? Could anybody give the outline for the same?

Also how can I check whether these values already exist in the user's document from client-side?

[yariplus]

How will the data be acquired? Where exactly will the data be displayed to users?

[cool]

I want to store the data in NodeBB's Mongo db. It will be retrieved later and displayed on a map..