code: function defineProp (obj, name, fn) {
    Object.defineProperty(obj, name, {
      enumerable: true,
      configurable: true,
      get: function () {
        return fn();
      }
    });
  }
docs: function App() {} Object.defineProperty(App.prototype, 'count', { get: function () { return Object.keys(this).length; } }); console.log(cu.getDescriptor(App.prototype, 'count'));