JS设计模式（二）getter setter

使用隐藏类信息的方法实现模拟getset

这是完全暴露类信息的代码

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

if(isbn == undefined) throw new Error('Book constructor requires an isbn.');

this.isbn = isbn;

this.title = title || 'No title specified';

this.author = author || 'No author specified';

}

Book.prototype.display = function() {

...

};

这是使用 Private Methods Using a Naming Convention 私有方法将信息隐藏

var Book = function(isbn, title, author) { // implements Publication

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('Book: Invalid ISBN.');

this._isbn = isbn;

},

getTitle: function() {

return this._title;

},

setTitle: function(title) {

this._title = title || 'No title specified';

},

getAuthor: function() {

return this._author;

},

setAuthor: function(author) {

this._author = author || 'No author specified';

},

display: function() {

...

}

};

第三种方法 Scope,Nested Functions, and Closures

var Book = function(newIsbn, newTitle, newAuthor) { // implements Publication

// Private attributes.

var isbn, title, author;

// Private method.

function checkIsbn(isbn) { //在方法内定义方法来隐藏

...

}

// Privileged methods.

this.getIsbn = function() {

return isbn;

};

this.setIsbn = function(newIsbn) {

if(!checkIsbn(newIsbn)) throw new Error('Book: Invalid ISBN.');

isbn = newIsbn;

};

this.getTitle = function() {

return title;

};

this.setTitle = function(newTitle) {

title = newTitle || 'No title specified';

};

this.getAuthor = function() {

return author;

};

this.setAuthor = function(newAuthor) {

author = newAuthor || 'No author specified';

};

// Constructor code.

this.setIsbn(newIsbn);

this.setTitle(newTitle);

this.setAuthor(newAuthor);

};

// Public, non-privileged methods.

Book.prototype = {

display: function() {

...

}

};

常量 Constants
Class.getUPPER_BOUND();
var Class = (function() {
// Constants (created as private static attributes).
var UPPER_BOUND = 100;
// Privileged static method.
this.getUPPER_BOUND() {
return UPPER_BOUND;
}
...
// Return the constructor.
return function(constructorArgument) {
...
}
})();

为了避免类的完整和独立，使用上述方法。！！！！