get set propoties in angular

var Element = (function() {
  function Element() {
    this._class = null;
  }
  Object.defineProperty(Element.prototype, 'className', {
    get: function() {
      return this._class;
    },
    set: function(name) {
      this._class = 'todd-' + name;
    },
    enumerable: true,
    configurable: true,
  });
  return Element;
})();