Backbone like getter and setter methods

gistfile1.js

var Car = function () {
    this.attributes = {
      color: null,
      wheels: 4,
      speed: null
    };
};

Car.prototype.set = function (key, value) {
    this.attributes[key] = value;
    return this;
};

Car.prototype.get = function (propKey) {
    return this.attributes[propKey];
};

myCar = new Car();
myCar.set('color', 'red')
     .set('wheels', 3)
     .set('speed', 'fast');

console.log( myCar.get('color') );