Meteor: Allow only one client instance per user

Question

Is there a way to prevent the user to open the Meteor website in two tabs or browsers?

I am trying to create a card game in Meteor, and I would like to "catch" if the user tries to open the page in another tab or browser and just warn him that another client instance is already opened and maybe give him/her the option to logout in all instances, etc.

I've googled already, but no luck.

Answer 1

If the users are required to log in:

• Save the connection to a Connections collection, along with user id. (or the roomId to the profile itself, depending on your schema)
• Remove the connection on disconnect
• on each new connection, see if the user id already exists in the Connections collection

If the users do not have to log in:

• Save the connection to a Connections collection (along with user IP)
• Remove the connection on disconnect
• on each new connection, see if the IP address already exists in the Connections collection

An example of using onConnection in the wild (note I don't disallow multiple connections, but that'd just be another 5 lines of code): https://github.com/mattkrick/react-tac-toe/blob/master/server/gameState.jsx#L13

The docs (ie how to capture ip address): http://docs.meteor.com/#/full/meteor_onconnection