Private posts in node js and socket io using php

I am developing a chat app using nodejs, socket.io and php, but I have a simple error in private messaging between two users. Therefore, I use the email id as a unique key for each user.

When user A sends a message to user B, he cannot read the messages until user B sends a message to user A after that, everything will work as expected.

chat.php

<form class="form-inline" id="messageForm">
    <input id="messageInput" type="text" class="input-xxlarge" placeHolder="Message" />
    <input type="hidden" name="" id="to" value="<?php echo $recevierid; ?>">
    <input type="submit" class="btn btn-primary" value="Send" />
</form>

      

        
        
        
      

    

Here the field hidden

contains the recipient's email id.

chat.js

$( "#messageForm" ).submit( function() {
    var msg = $( "#messageInput" ).val();
    var to =$( "#to" ).val();
    socket.emit('join', { message:msg,to:to} );
    $( "#messageInput" ).val('');
    return false;
});
socket.on( 'new_msg', function( data ) {
    var actualContent = $( "#messages" ).html();
    var newMsgContent = '<li>: ' + data.message + '</li>';
    var content = newMsgContent + actualContent;    
    $( "#messages" ).html( content );
});

      

        
        
        
      

    

nodeServer.js

var socket = require( 'socket.io' );
var express = require( 'express' );
var http = require( 'http' );

var app = express();
var server = http.createServer( app );

var io = socket.listen( server );

io.sockets.on( 'connection', function( client ) {
    console.log( "New client !" );

    client.on('join', function( data ) {
        console.log( 'Message received' + data.message+"email"+data.to);
        client.join(data.to);
        io.sockets.in(data.to).emit("new_msg",{message:data.message});
    });
}); 

server.listen( 8080 );