private chat using socket.id on socket.io - angularjs

Question

i am fresher at nodejs and socket.io. i am trying to made a chat application using nodejs, socket.io and angularjs in express framework. i am lacking basic idea how chat is performed privately.up to this stage my code works chatting in a group of connected users. here is my server code
var server = require('http').Server(app);
var io = require('socket.io')(server);
var socket = require('./routes/socket.js');
server.listen(8000);
console.log('server listening on port:8000');
io.on('connection',socket);
and my main socket file consit code like:
module.exports = function(socket){
console.log('connected'+' '+'socketId :'+socket.id);
//console.log(req.session.id);
var users =[];
socket.emit(socket.id);
socket.on('username',function(data){
users.push({id:socket.id,message:data.username});
socket.emit('username', users)
})
socket.on('typing',function(data){
//socket.emit('typing',{message:"helo angular"});
socket.broadcast.emit('typing',{message:data.message});
});
socket.on('typing-stop',function(data){
//socket.emit('typing',{message:"helo angular"});
debugger;
socket.broadcast.emit('typing-stop',{message:data.message});
});
socket.on('new-user',function(data){
socket.emit('new-user',data);
socket.broadcast.emit('new-user',data);
})
socket.on('message',function(data){
users.push({message:data.message});
socket.emit('message',{id:socket.id,message:data.message});
socket.broadcast.emit('message',{id:socket.id,message:data.message});// emit the message to every one connected in server
})
socket.on('disconnect',function(){
console.log('user disconnected');
socket.broadcast.emit('disconnected',{'message':'user left the chat room'});
});
}
i am abe to load all the users who get logged in my app.
all i want is to click to the available and start private messaging, till now chat is public everyone connected in server can see message.
my angularjs controller code goes like:
function orgController(notifyService, chatSocket, $state,$http) {
chatSocket.connect();
var vm = this;
vm.sendMessage = sendMessage;
vm.messages = [];
vm.users = [];
var id = $state.params.id;
$http.get('/users/' + id).then(function(result) {
console.log(result.data);
vm.userData = result.data;
chatSocket.emit('new-user', { 'username': result.data.details.firstName + ' ' + result.data.details.lastName });
});
chatSocket.on('new-user',function(data){
vm.users.push(data);
})
function sendMessage(msg) {
//console.log(msg);
if (msg != null && msg != '') {
chatSocket.emit('message', { message: msg });
vm.msg = '';
} else {
vm.msg = '';
}
}
chatSocket.on('message', function(data) {
//debugger;
console.log(data);
vm.messages.push(data);
});
}
NOTE: i have included angular-socket.io modules and inject its dependency in a service called chatSocket which only return socketFactory.
now i want to click in a user from logged in userlist and start communication. how can i do it from (socket.id). which socket generates or from session id? anyone has better way of doing such. any suggestion and response are highly appreciated.

Answer 1

Basically what you need to do is emit an event to a specific socket like this.
io.to(socket.id).emit('privateMessage', {message: <message goes here>});
then on the client side
socket.on('privateMessage', function(data){
var message = data.message;
//do stuff, display message etc...
});