工厂模式

1.简单工厂

/* BicycleShop class. */

var BicycleShop = function() {};
BicycleShop.prototype = {
  sellBicycle: function(model) {
    var bicycle;
    
    switch(model) {
      case 'The Speedster':
        bicycle = new Speedster();
        break;
      case 'The Lowrider':
        bicycle = new Lowrider();
        break;
      case 'The Comfort Cruiser':
      default:
        bicycle = new ComfortCruiser();
    }
    Interface.ensureImplements(bicycle, Bicycle);
    
    bicycle.assemble();
    bicycle.wash();
    
    return bicycle;
  }
};


/* The Bicycle interface. */

var Bicycle = new Interface('Bicycle', ['assemble', 'wash', 'ride', 'repair']);

/* Speedster class. */

var Speedster = function() { // implements Bicycle
  ...
};
Speedster.prototype = {
  assemble: function() {
    ...
  },
  wash: function() {
    ...
  },
  ride: function() {
    ...
  },
  repair: function() {
    ...
  }
};


/* Usage. */

var californiaCruisers = new BicycleShop();
var yourNewBike = californiaCruisers.sellBicycle('The Speedster');



/* BicycleFactory namespace. */

var BicycleFactory = {
  createBicycle: function(model) {
    var bicycle;
    
    switch(model) {
      case 'The Speedster':
        bicycle = new Speedster();
        break;
      case 'The Lowrider':
        bicycle = new Lowrider();
        break;
      case 'The Comfort Cruiser':
      default:
        bicycle = new ComfortCruiser();
    }
    
    Interface.ensureImplements(bicycle, Bicycle);
    return bicycle;
  }
};

/* BicycleShop class, improved. */

var BicycleShop = function() {};
BicycleShop.prototype = {
  sellBicycle: function(model) {
    var bicycle = BicycleFactory.createBicycle(model);
    
    bicycle.assemble();
    bicycle.wash();
    
    return bicycle;
  }
};

/* BicycleFactory namespace, with more models. */

var BicycleFactory = {
  createBicycle: function(model) {
    var bicycle;
    
    switch(model) {
      case 'The Speedster':
        bicycle = new Speedster();
        break;
      case 'The Lowrider':
        bicycle = new Lowrider();
        break;
      case 'The Flatlander':
        bicycle = new Flatlander();
        break;
      case 'The Comfort Cruiser':
      default:
        bicycle = new ComfortCruiser();
    }
    
    Interface.ensureImplements(bicycle, Bicycle);
    return bicycle;
  }
};

2.工厂模式

/* BicycleShop class (abstract). */

var BicycleShop = function() {};
BicycleShop.prototype = {
  sellBicycle: function(model) {
    var bicycle = this.createBicycle(model);
    
    bicycle.assemble();
    bicycle.wash();
    
    return bicycle;
  },
  createBicycle: function(model) {
    throw new Error('Unsupported operation on an abstract class.');
  }
};

/* AcmeBicycleShop class. */

var AcmeBicycleShop = function() {};
extend(AcmeBicycleShop, BicycleShop);
AcmeBicycleShop.prototype.createBicycle = function(model) {
  var bicycle;

  switch(model) {
    case 'The Speedster':
      bicycle = new AcmeSpeedster();
      break;
    case 'The Lowrider':
      bicycle = new AcmeLowrider();
      break;
    case 'The Flatlander':
      bicycle = new AcmeFlatlander();
      break;
    case 'The Comfort Cruiser':
    default:
      bicycle = new AcmeComfortCruiser();
  }

  Interface.ensureImplements(bicycle, Bicycle);
  return bicycle;  
};

/* GeneralProductsBicycleShop class. */

var GeneralProductsBicycleShop = function() {};
extend(GeneralProductsBicycleShop, BicycleShop);
GeneralProductsBicycleShop.prototype.createBicycle = function(model) {
  var bicycle;

  switch(model) {
    case 'The Speedster':
      bicycle = new GeneralProductsSpeedster();
      break;
    case 'The Lowrider':
      bicycle = new GeneralProductsLowrider();
      break;
    case 'The Flatlander':
      bicycle = new GeneralProductsFlatlander();
      break;
    case 'The Comfort Cruiser':
    default:
      bicycle = new GeneralProductsComfortCruiser();
  }

  Interface.ensureImplements(bicycle, Bicycle);
  return bicycle;
};


/* Usage. */

var alecsCruisers = new AcmeBicycleShop();
var yourNewBike = alecsCruisers.sellBicycle('The Lowrider');

var bobsCruisers = new GeneralProductsBicycleShop();
var yourSecondNewBike = bobsCruisers.sellBicycle('The Lowrider');