Object.createを使ったMixInのサンプル

object_create_mix_in.js

/*
* Object.create(): the New Way to Create Objects in JavaScript
* http://www.htmlgoodies.com/beyond/javascript/object.create-the-new-way-to-create-objects-in-javascript.html
*/


var Car2 = Object.create(null); //this is an empty object, like {}
Car2.prototype = {
  getInfo: function() {
    return 'A ' + this.color + ' ' + this.desc + '.';
  }
};
 
var car2 = Object.create(Car2.prototype, {
  //value properties
  color:   { writable: true,  configurable:true, value: 'red' },
  //concrete desc value
  rawDesc: { writable: false, configurable:true, value: 'Porsche boxter' },
  // data properties (assigned using getters and setters)
  desc: { 
    configurable:true, 
    get: function ()      { return this.rawDesc.toUpperCase();  },
    set: function (value) { this.rawDesc = value.toLowerCase(); }  
  }
}); 
car2.color = 'blue';
alert(car2.getInfo()); //displays 'A RED PORSCHE BOXTER.'