General Info

I'm currently working on a chatsystem using a websocket. Aside from the messages, I'm using the same websocket to present the user with a userlist of those currently online.

The Problem

Since a couple of days I've been trying to script all of my Javascript purely in OOP approach. So far it's going pretty well but now I've stumpled upon a error I honestly don't understand:

Argument 1 of Node.appendChild is not an object

The Code

I've narrowed down my code as far as possible to only represent the important parts:

var CB = CB || {};



CB.messages = {

    userListLayout: function(Username){

        var userListTable = <table class='userTable' data-user='+ Username +'><tbody><tr><td><img src='layout/images/default_profile.png'></td><td> + Username + </td></tr></tbody></table>;



        return userListTable;

    }

}



CB.users = {

    set: function(Usernames) {

        var List = document.getElementById('usersList'); // Represents an empty div

        var i, j = Usernames.length, ListUser;



        for (i=0; i<j; i++) {

            ListUser = CB.messages.userListLayout(Usernames[i]);

            List.appendChild(ListUser); // Error

        }

    }

}

So the question is: What am I doing wrong and what's the best way to fix it?