firebase - Does a firebase client using only 'once()' callbacks count as a concurrent user?

Question

I have read online that a concurrent user is defined as a client that has an on() callback listening for updates on your data. If I use the once() method instead throughout my app (in other words, I'm just using firebase as a data store) will the client still count as a concurrent user?

Answer 1

Yes it will. We count the number of clients (browser tabs or mobile devices) with open connections to us. We open a connection to the Firebase servers as soon as you say new Firebase(url);, and we leave it open so that all future requests will be fast (otherwise, the next time you did a once or any other operation we'd have to reestablish a connection again, which would slow things down).