javascript设计模式7

链式调用

(function(){
    function _$(els){
        //...
    }
    _$.prototype={
        each:function(fn){
            for(var i=0,len=this.elements.length;i<len;++i){
                fn.call(this,this.elements[i]);
            }
            return this;
        },
        setStyle:function(prop,val){
            this.each(function(el){
                el.style[prop]=val;
            });
            return this;
        },
        show:function(){
            var that=this;
            this.each(function(el){
                that.setStyle('display','block');
            });
            return this;
        },
        addEvent:function(type,fn){
            var add=function(el){
                if(window.addEventListener){
                    el.addEventListener(type,fn,false);
                }
                else if(window.attachEvent){
                    el.attachEvent('on'+type,fn);
                }
            };
            this.each(function(el){
                add(el);
            });
            return this;
        }
    };
    window.$=function(){
        return new _$(arguments);
    };
})();

从支持链式调用的方法获取数据

window.API=window.API||function(){
    var name='Hello World';
    this.setName=function(newName){
        name=newName;
        return this;
    };
    this.getName=function(callback){
        callback.call(this,name);
        return this;
    };
};
var o2=new API;
o2.getName(console.log).setName('Meow').getName(console.log);

简单工厂

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;
    }

};

把成员对象的创建工作交给外部对象

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);
    }
};

工厂模式（不是使用另外一个类或对象创建，而是使用子类创建）

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('...')//抽象类，声明这个方法，但不实现这个方法，直接调用会报错
    }
};

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 Comfort Cruiser':
        default:
        bicycle=new AcmeComfortCruiser();
    }
    Interface.ensureImplements(bicycle,Bicycle);
    return bicycle;
};
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 Comfort Cruiser':
        default:
        bicycle=new GeneralProductsComfortCruiser();
    }
    Interface.ensureImplements(bicycle,Bicycle);
    return bicycle;
};
//需要时任意调用即可
//var bobCruisers=new GeneralProductsBicycleShop();
//var yourSecondNewBike=bobCruisers.sellBicycle('The Lowrider');