JavaScript 设计模式 － Factory(工厂模式) 示例1

javascript-factory-pattern-example1.js

//父构造函数
function CarMaker() { }

//所有子类通用方法
CarMaker.prototype.drive = function () {
  console.log( "Vroom, I have " + this.doors + " doors");
};

//静态工厂方法 子类无法继承
CarMaker.factory = function(type) {
  var constr = type,
      newcar;

  //如果构造函数不存在，则发生错误
  if(typeof CarMaker[constr] !== "function") {
    throw {
      name: "Error",
      message: constr + " doesn't exist"
    };
  }

  //继承父类，但仅继承一次
  if(typeof CarMaker[constr].prototype.drive !== "function") {
    CarMaker[constr].prototype = new CarMaker();
  }

  newcar = new CarMaker[constr]();

  return newcar;
};

// 定义不同的子对象
CarMaker.Compact = function() {
  this.doors = 4;
};
CarMaker.Convertible = function() {
  this.doors = 2;
};
CarMaker.SUV = function() {
  this.doors = 24;
};

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

//Vroom, I have 4 doors
//Vroom, I have 2 doors
//Vroom, I have 24 doors