I'm working on this simple tic-tac-toe app and whenever a player hits a button it will trigger the function markTheCell(button) passing the button's id. This function then emits the player which is string value and the button id to the server. I put console log in the client page to see whether a valid value is being passed and it is. But when I tried to log it in the server the value of the player become object Object and the button id is undefined. I don't know if I failed how to put and use the parameters correctly. Hope someone lend a help because I'm stuck with this.
index.html
<body> <div class="col-lg-4"></div> <div class="col-lg-4 jumbotron"> <h4>You are player <span id="name"></span></h4> <button id="one" onclick="markTheCell(this.id)" class="btn btn-default"></button> <button class="btn btn-default"></button> <button class="btn btn-default"></button></br> <button class="btn btn-default"></button> <button class="btn btn-default"></button> <button class="btn btn-default"></button></br> <button class="btn btn-default"></button> <button class="btn btn-default"></button> <button class="btn btn-default"></button> </div> <div class="col-lg-4"></div> </div> <script src="/socket.io/socket.io.js"></script> <script> var socket = io(); var player = ""; $(document).ready(function () { socket.on('player', function (playerNo) { player = playerNo; $('#name').text(playerNo); }); socket.on('hitAMark', function (player, button) { console.log("in client hit a mark player "+ player); console.log("in client hit a mark button "+ button); $(button).text(player); }); }) function markTheCell(button) { socket.emit('mark', {player,button }); console.log("in markTheCell client hit a mark player "+ player); console.log("in markTheCell client hit a mark button "+ button); } </script> </body> index.js
var player = 0; io.on('connection', function(socket){ if(player==0){ player++; socket.emit('player', "X"); console.log("Player "+ player +" is connected"); }else if(player==1){ player++; socket.emit('player', "O"); console.log("Player "+ player +" is connected"); } socket.on('disconnect', function(){ console.log('A user is disconnected'); }); socket.on('mark', function(player, button){ console.log("in server hit a mark button "+ player); console.log("in server hit a mark player "+button); io.emit('hitAMark', {player,button}); }); }); http.listen(3000, function(){ console.log('Server is listening on port 3000!'); }); The screenshot of the console in browser and cmd: 
