javascript设计模式-掺元类

有一种重用代码的方法不需要用到严格的继承。如果想把一个函数用到多个类中，可以通过扩充的方式让这些类共享该函数。其实际做法大大体为：先创建一个包含各种通用方法的类，然后再用它扩充其他的类。这种方式就叫做掺元类。

function augment(receivingClass,givingClass){
    if(arguments.length > 2){
        for(var i= 2, len = arguments.length;i<len;i++){
            receivingClass.prototype[arguments[i]] = givingClass.prototype[arguments[i]];
        }
    }else{
        for(var methodName in givingClass.prototype){
            if(!receivingClass.prototype[methodName]){
                receivingClass.prototype[methodName] = givingClass.prototype[methodName];
            }
        }
    }
}

function Author(name,books){
    this.name = name;
    this.books = books;
}
Author.prototype.getBooks = function(){
    return this.books;
}

var MiXin = function(){};
MiXin.prototype = {
    serialize:function(){
        var output = [];
        for(key in this){
            output.push(key + ":" + this[key]);
        }
        return output.join(", ");
    }
}
augment(Author,MiXin);
var author = new Author("zap","读书笔记");
console.log(author.serialize());