Making JS classier. Until moving on to something with classiness baked-in that compiles to JS :)

classy.js

// Requires ES5

// Inheritance pattern inspired by http://stackoverflow.com/a/5546053

// instanceOf has the usual straightforward-inheritance-checker problems with iFrames

if (typeof classyJS === 'undefined') {
   var classyJS = (function () {
      'use strict';

      var my = Object.create(null);

      my.NullObj = function () { return Object.create(null); };

      my.$super  = function (cls) { return cls._parent; };

      my.instanceOf = function (inst, cls) {
         if (typeof cls.prototype === 'undefined') return false;
         else return Object.isPrototypeOf.call(cls.prototype, inst);
      };

      var extend = function (cls) {
         var subcls = my.NullObj();

         subcls.prototype = Object.create(cls.prototype);

         subcls.create    = function () {
            var inst = Object.create(subcls.prototype);
            if (inst.init instanceof Function) inst.init.apply(inst, arguments);
            return inst;
         };

         subcls.extend  = function () { return extend(subcls); };

         subcls._parent = cls;

         return subcls;
      };

      my.BaseObj = (function () {
         var cls = my.NullObj();
         cls._parent = null;
         cls.prototype = my.NullObj();

         cls.prototype.instanceOf = function (kls) {
            return my.instanceOf(this, kls);
         };

         cls.extend = function() { return extend(cls); };

         cls.create = function() { return Object.create(cls.prototype); };

         return cls;

      }());

      return my;

   }());
}
else alert('Namespace collision while loading classyJS library.');