javascript设计模式3

门户大开式对象

var Book=function(isbn,title,author){

    if (isbn==undefined) throw new Error("不合法");

    this.isbn=isbn;

    this.title=title||'无标题';

    this.author||'无作者';

}

Book.prototype.display=function(){

    ...

};

强化版本

var Book=function(isbn,title,author){

    if (!this.checkIsbn(isbn)) throw new Error("ISBN无效");

    this.isbn=isbn;

    this.title=title||'无标题';

    this.author||'无作者';

}

Book.prototype={

    checkIsbn:function(isbn){

        if (isbn==undefined||typeof isbn!='string') {

            return false;

        }

        isbn=isbn.replace(/-/,'');

        if (isbn.length!=10 &&isbn.length!=13) {

            return false;

        }

        var sum=0;

        if (isbn.length===10) {

            if(!isbn.match(/^\d{9}/)){

                return false;

            }

            for(var i=0;i<9;i++){

                sum +=isbn.charAt(i)*(10-i);

            }

            var checksum=sum%11;

            if(checksum===10)checksum='X';

            if (isbn.charAt(9)!=checksum) {

                return false;

            }

        }

        else{

            if(!isbn.match(/^\d{12}/)){

                return false;

            }

            for(var i=0;i<12;i++){

                sum+=isbn.charAt(i)*((i%2===0)?1:3);

            }

            var checksum=sum%10;

            if(isbn.charAt(12)!=checksum){

                return false;

            }

        }

        return true;

    },

    display:function(){

        ...

    }

};

 更进一步

var Publication=new Interface('Publication',['getIsbn','setIsbn','getTitle','setTitle','getAuthor','setAuthor','display']);

var Book=function(isbn,title,author){

    this.setIsbn(isbn);

    this.setTitle(title);

    this.setAuthor(author);

}

Book.prototype={

    checkIsbn:function(isbn){

        ...

    },

    getIsbn:function(){

        return this.isbn;

    },

    setIsbn:function(isbn){

        if(!this.checkIsbn(isbn)) throw new Error("ISBN不合法");

        this.isbn=isbn;

    },

    getTitle:function(){

        return this.title;

    },

    setTitle:function(title){

        this.title=title||"无标题";

    },

    getAuthor:function(){

        return this.author;

    },

    setAuthor:function(author){

        this.author=author||"无作者";

    },

    display:function(){

        ...

    }

};

 为了防止其他程序员的无意使用，可以在私有方法和属性前加_表明是私有

用闭包实现私用成员

var Book=function(newIsbn,newTitle,newAuthor){

    var isbn,title,author;

    function checkIsbn(isbn){

        ...

    }

    this.getIsbn=function(){

        return isbn;

    };

    this.setIsbn=function(newIsbn){

        if(!checkIsbn(newIsbn)) throw new Error("ISBN不合法");

        isbn=newIsbn;

    };

    this.getTitle=function(){

        return title;

    };

    this.setTitle=function(newTitle){

        title=newTitle||'无标题';

    };

    this.getAuthor=function(){

        return author;

    };

    this.setAuthor=function(newAuthor){

        author=newAuthor||'无作者';

    };

    this.setIsbn(newIsbn);

    this.setTitle(newTitle);

    this.setAuthor(newAuthor);

};

Book.prototype={

    display:function(){

        ...

    }

};