Javascript Proper Class constructor

Question

I am trying to create a class that in its constructor uses some helper functions. Is there a way to move these helpers to the prototype? The problem is that the constructor does

Answer 1

I want to move stuff to the prototype, because if I understood correctly, these functions are not tied to a single object, so if I have multiple objects they will still call the same code but with different context.

Yes. However, that is not what you want: The asynchronous callbacks need to be tied on specific instances.

If you don't want to have too much stuff floating around your constructor, you might reconsider your design:

function Class(model) {
    this.id = model._id;
    this.core = model;
}
Class.prototype.addPlayer = function(player, callback) {
    gameOps.addPlayer(player, this.model, callback);
};
Class.fromDatabase = function(id, callback) {
    function addCore(err, model) {
        if (err)
            callback(err);
        else
            callback(null, new Class(model))
    }
    function addTopology() {
    }

    if (arguments.length === 2) {
        gameOps.findById(id, addCore)
    } else {
        callback = id
        gameOps.create(addCore)
    }
}