工廠模式

factory.js

var corolla = CarMaker.factory('Compact');
var solstice = CarMaker.factory('Convertible');
var cherokee = CarMaker.factory('SUV');

corolla.drive();   // "Vroom , I have 4 doors"
soIstice.drive();  // "Vroom , I have 2 doors"
cherokee.drive(); // "Vroom , I have 17 doors"

// 父建構式 
function CarMaker(){} 

//父建樣式的一個方法 
CarMaker.prototype.drive = function() { 
  return "Vroom, I have " + this.doors + " doors";
};

// 靜態的工廠方法
CarMaker.factory = function (type) { 
  var constr = type, 
       newcar; 

  // 建構式不存在則拋出错误 
  if ( typeof CarMaker[constr] !== “function" ) { 
    throw {
      name : " Error ", 
      message : constr + " doesn't exist";
    };
  }

  // 到這裡我們已經知道建構式存在了
  // 我們讓它繼承父建構式，但僅此一次 
  if ( typeof CarMaker[constr].prototype.drive !== " function" ) { 
  CarMaker[constr].prototype = new CarMaker();
  }

  // 建立新實體
  newcar = new CarMaker[constr](); 
  // 選擇性的呼叫一些方法 , 然後回傳
  return newcar; 
};

// 定義具體的 car maker 
CarMaker.Compact = function() { 
  this.doors = 4; 
}; 
CarMaker.Convertible = function() { 
  this.doors = 2; 
};
CarMaker.SUV = function() { 
  this.doors = 24; 
};