JavaScript装饰者模式：通过汽车组装实例解析动态扩展功能

//定义一个静态方法来实现接口与实现类的直接检验
//静态方法不要写出Interface.prototype ,因为这是写到接口的原型链上的
//我们要把静态的函数直接写到类层次上
//定义一个接口类
var Interface=function (name,methods) {//name：接口名字
  if(arguments.length<2){
    alert("必须是两个参数")
  }
  this.name=name;
  this.methods=[];//定义一个空数组装载函数名
  for(var i=0;i<methods.length;i++){
    if(typeof methods[i]!="string"){
      alert("函数名必须是字符串类型");
    }else {
      this.methods.push( methods[i]);
    }
  }
};
Interface.ensureImplement=function (object) {
  if(arguments.length<2){
    throw new Error("参数必须不少于2个")
    return false;
  }
  for(var i=1;i<arguments.length;i++){
    var inter=arguments[i];
    //如果是接口就必须是Interface类型
    if(inter.constructor!=Interface){
      throw new Error("如果是接口类的话，就必须是Interface类型");
    }
    //判断接口中的方法是否全部实现
    //遍历函数集合分析
    for(var j=0;j<inter.methods.length;j++){
      var method=inter.methods[j];//接口中所有函数
      //object[method]传入的函数
      //最终是判断传入的函数是否与接口中所用函数匹配
      if(!object[method]||typeof object[method]!="function" ){//实现类中必须有方法名字与接口中所用方法名相同
        throw new Error("实现类中没有完全实现接口中的所有方法")
      }
    }
  }
}

var ShopInterface=new Interface("FirstShop",["getPrice","assemble"]);//规定了实现的方法

var first=function () {
    //接口实现部分
    this.getPrice=function () {
      document.write(15000+"<br>")
    }
    this.assemble=function () {
     document.write("汽车组装....<br>")
    }
    Interface.ensureImplement(this,ShopInterface);//检验类是否实现接口
}

//第一个汽车实例
var firstShop=new first();
firstShop.getPrice();
firstShop.assemble();
document.write("...............first...............<br>")

var SecondInterface=new Interface("SecondInterface",["getPrice","assemble","addK","addM","addN"]);

var second=function () {
     var price=15000;
     //实例接口部分
     this.getPrice=function () {
       document.write(price+"<br>")
     }
     this.assemble=function () {
       document.write("汽车组装.....<br>");
     }
     this.addK=function () {
       price+=1000;
     }
     this.addM=function () {
       price+=2000;
     }
     this.addN=function () {
       price+=3000;
     }
     Interface.ensureImplement(this,SecondInterface);//当前对象实例时会被调用
}

//第二个汽车实例
var secondShop=new second();
 secondShop.addK();
 secondShop.addM();
 secondShop.addN();
 secondShop.getPrice();
 secondShop.assemble();
 document.write(".....................second.........................<br>");

var thirdInterface=new Interface("FirstShop",["getPrice","assemble"]);

var third=function () {
  this.getPrice=function () {
    document.write(15000+"<br>");
  }
  this.assemble=function () {
    document.write("汽车组装.....<br>");
  }
  Interface.ensureImplement(this,thirdInterface);
}

var thirdM=function () {
  this.getPrice=function () {
    document.write(15000+"<br>");
  }
  this.assemble=function () {
    document.write("汽车组装.....<br>");
  }
  Interface.ensureImplement(this,thirdInterface);
};

var comInterface=new Interface("FirstShop",["getPrice","assemble"]);

var targetShop = function(){
    this.getPrice = function(){
      return 15000;
    }
    this.assemble =function(){
      document.write("汽车组装....<br>")
    }
    Interface.ensureImplement(this,comInterface);//接口检验
}

var carM = function(carShop) {
    this.getPrice = function () {
      return 1000 + carShop.getPrice();
    }
    this.assemble = function () {
      document.write("M组装....<br>")
    }
    Interface.ensureImplement(this,comInterface);//接口检验
}

var carN = function(carShop){
    this.getPrice = function(){
      return 2000+carShop.getPrice();
    }
    this.assemble =function(){
      document.write("N组装....<br>")
    }
    Interface.ensureImplement(this,comInterface);//接口检验
}

 var carK=function (carShop) {
    this.getPrice=function () {
      return 3000+carShop.getPrice();
    }
    this.assemble=function () {
      document.write("K组装....<br>")
    }
    Interface.ensureImplement(this,comInterface);//接口检验
};

//包装车
var newCar=new carK(new carM(new targetShop));//有K和M的车
var newCar2=new carK(new carM(new carN(new targetShop)));
document.write(newCar.getPrice()+"<br>");
document.write(newCar2.getPrice());