function Obj(data){

    var hash = objs[data.type] ? objs[data.type] : objs[data.type] = {};

    this.expensiveProperty = data;

    //other logic

    hash[json.id] = this;
}

function Player(data, socket){
    var thisObj = this;

    Obj.call(this, data);

    this.vars.private['name'] = data.name;

    socket.player = this;
    this.socket = socket;
}
Player.prototype = Object.create(Obj.prototype);
Player.prototype.constructor = Obj;
Player.prototype.emit = function(data){
    this.socket.emit(data);
}

new Player({type:'type1', ...});
new Player({type:'type2', ...});
new Player({type:'type3', ...});

function instancePlayer(){
    return Object.create( objs['player']['type1'] );
}