Answer from socket.io returns OBJECT OBJECT

I am creating a chat in php and nodejs using library socket.io the thing is that from my index.php I make a call ajax that inserts the data in the database and I return the answer through a array to ajax, then I send that data with socket.io with emit() , but at the time of reading that data returns [object Object] .

THIS IS MY CODE

const http = require('http');
const path = require('path');
const express = require('express');
const connect = require('connect');
const app = express();
const server = app.listen(3000);
const io = require('socket.io').listen(server);

io.on('connection',socket=>{
    console.log('NEW  CLIENT');

    //esta es la accion que se recive desde el cliente
socket.on('client-message',function (data) {
     console.log(data);

    //aqui el servidor emite el mensaje a todos los clientes
    io.sockets.emit('server-message', data);
})

 })


 //voy a establecer un puerto si no tomas el 3000
 app.set('port' , process.env.PORT || 3000)


//voy a recivir el puerto
server.listen(app.get('port') ,()=>{

    console.log('conectado con el servidor '+app.get('port'))
})

call ajax

<?php
    session_starts();

     $msg=$_POST['msg'];
     $id=$_POST['id'];
     $yo=$_SESSION['id'];
   $insert=mysqli_query(INSERT INTO message(msg,de,para,fecha)VALUES('$msg','$yo','$id',now()) ");

$query=mysqli_query($conexion,"SELECT * FROM registro WHERE id='$yo' ");
                   $row=mysqli_fetch_array($query);

$my_pic=$row['avatar'];

echo json_encode(array('pic'=>$my_pic,'msng'=>$msg);

?

customer

$(function () {


var sockets = io.connect( 'http://localhost:8080/' );

   //obteniendo los elementos del Dom 

   var formulario = $("#message-form");
   var mensajebox = $("#chat");
   var myMessage = $("#message");
   var myId = $("#id");

    formulario.submit( e =>{

        e.preventDefault();
        //console.log(mensaje.val());

   //emitimos mensaje al servidor

   $.ajax({

        url:"insert_message.php",
        type:"POST",
        data:formulario.serialize(),
        datatype:"json",
        success:function(data){

//recivimos el array desde php y lo enviamos al servidor
         socket.emit('client-message',data);
        //limpiar input despues de enviar
           myMessage.val("");
      }
   })


    });


  /*aqui nos toca escuchar el mensaje atraves de la palabra clave del servidor*/

    socket.on('server-message',function(data){

        //aqui elegimos donde mostrar el mensaje del servidor
            mensajebox.append(data.pic + data.msg+'<br>');
    });
})

In the server console my array is reflected very well, like this: <"pic","andy.png","msg","hola soy andy"> . As you can see what I want is to show my photo and my message.
Any ideas or tips on how to do it, no novice with arrays and json?