How to send message to one user (it broadcast for all user)?

[vqquoc]

When i send messenger from user A to user B
app.BrainSocket.message('chat.event', { 'message': msg, 'userIdSend':userIdSend, 'userIdReceived':userIdReceived });
From user B, i check then show messenger
From another user, i don't show it, But i check in console windown, i see message broadcast to all user.

How to send message from user A to user B, another user can't see it?