To be entirely blunt, I'd be cautious about pursuing this idea. People wanting to develop MMOs are usually treated as a joke among programmers because of the severe amount of work that an MMO requires. Games alone are a lot of work, but MMOs are far, far worse due to the multiplayer aspect, dealing with scaling, and preventing cheating.
Your code does not work, so I cannot say if you're at the stage where you can realistically do an MMO. Have you created a single player game first? That's a good way to test skill. Art is the easy part; code is where all the work is (well, it's not truly easy, but you can get away with crappy art, but crappy code won't work at all).
Your platform raises some questions. The client side is entirely doable in JS, but the server side is far iffier. And you need a server side. I mean, in theory, you could use WebRTC to create an entirely P2P MMO. You'd still need a signalling channel, but in theory, you could get rid of that by swapping all the necessary signalling information (offer, answer, ICE candidates) over a medium like email, IRC, etc. I guess you can tell that I've been using WebRTC a lot lately. But that's not scaleable, anyway, so a central server is a necessity for any serious game. And this central server has to do a LOT of work. The only effective way to stop cheating is to have the server (under your control) do most of the work, with clients mostly being treated as mostly just GUIs. So the server needs optimal performance, for which JS is a poor choice.
Not trying to discourage you from doing fun programming side projects, but if you don't know what you're doing (and honestly, this is one of those "if you have to ask such vague questions, you're not ready" cases), things will rarely work out. So you may end up wasting your time that could be better put towards, say, making a single player game or some other form of stepping stone. As a skill testing trial, I would expect that you'd be able to make at least a single player game and something like a multi-player chess game (etc) where the server does all the work before you try an MMO.
For a more comical approach to my point see this thread about someone trying to make a 100% dragon MMO