JavaScript design mode new Create Safe mode for objects

for us beginners, when using JS to create objects, do not adapt to the closure of the writing, often easy to forget to use the new keyword and make mistakes.

A closure is a function that has access to a variable in another function scope, that is, creating another function inside a function. We use this closure as the constructor for creating an object so that he can access the variable in the scope of the class function, such as the booknum variable, when it is both a closure and a function of the instantiated object, and the variable is called a static private variable, and checkbook () is called a static private method. Of course the closure also has its own private variables and private methods such as Price,checkid ().

Using closure to implement
Var book= (function () {
//static private variable
var booknum = 0;
Create Private method
function Checkbook (name) {}
//Create class
function book (newid,newname,newprice) {
    //private variable
    var Name,price;
    Private method
    function Checkid (id) {}
    //Privileged Method
    This.getname=function () {};
    This.getprice=function () {};
    This.setname=function () {};
    This.setprice=function () {};
    public attribute
    This.id=newid;
    Public method
    This.copy=function () {};
    booknum++
    if (booknum>100) {
        throw new Error (' No more books. ')
    This.setname (name);
    This.setprice (price);
}
    Building
    a prototype _book.prototype={
        //Static public property
        Isjsbook:false,
        //Static Common method
        Display:function () {}
    };
    Returns class return
    _book;
}) ();

New Create Class

Books
var book = function (title,time,type) {
    this.title = title;
    This.time = time;
    This.type = type;
}
Instantiate a book
var = books (' JavaScript ', ' 2014 ', ' JS ');

Results:
console.log (book),//undefined
Console.log (window.title),//javascript
Console.log (window.time) ; 2014
Console.log (window.type);//js

The New keyword action can be seen as a constant assignment of this to the current object, but the example does not use new, so the function is executed directly, and the function is executed in the global scope, so this point in the global scope is the current object, which is naturally a global variable, Global variable is window in page

Therefore, you can use the following security mode:

//Books security class var book = function (Title,time,type) {//Determine whether this is the current object in the execution (if the description is created with new) if (this
        instanceof book) {this.title = title;
        This.time = time;
        This.type = type;
    Otherwise recreate this object}else{return new book (Title,time,type);


} var book= book (' JavaScript ', ' 2014 ', ' JS '); Output Result: Console.log (book); Book Console.log (Book.title); JavaScript console.log (book.time); 2014 Console.log (Book.type); JS Console.log (Window.title); Undefined Console.log (window.time); Undefined Console.log (window.type); Undefined