Argument 1 of Node.appendChild is not an object when trying to append basic html

Question

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?

Answer 1

ListUser is a string of HTML. Node.appendChild only accepts a DOM node as an argument.

https://developer.mozilla.org/en-US/docs/Web/API/Node/appendChild

You have two options here, either wrap the text you want in a node and use appendChild or keep the current setup and use innerHTML which allows you to add a string to the HTML document:

List.innerHTML += ListUser