Class in the JavaScript this is a common constructor function. Such a constructor function contains simple data, objects, internal functions in the JavaScript. To create a class object, use new Example: function Book() { ... } ... var obj1 = new Book();

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Class in the JavaScript this is a common constructor function. Such a constructor function contains simple data, objects, internal functions in the JavaScript. To create a class object, use new Example: function Book() { ... } ... var obj1 = new Book(); | стандарт ES5

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Class in the JavaScript it is a constructor function | стандарт ES5

last updated: 31 July 2020

Class is constructor function, so it is Normal function in JavaScript...

// определяем класс (функция-коснструктор)
function MyBook(name)
{
     ...
     // BookName это внутренняя переменная
     var BookName = ;

     // Price это внешняя переменная
     this.Price = 0;
     ...
}

A class (constructor function) can contain:
• internal variables: text, numbers, flags, date, array, property set
• external variables: text, numbers, flags, date, array, property set
• internal functions
• External links
• static functions

Example

Html

<html>
<body>


<h1>Hello!</h1>

<script language='JavaScript'>

     // define a class MyBook
     function MyBook(name)
     {
          // BookName it's an internal variable
          // BookName NOT visible from the outside because it is declared as var
          var BookName = name;

          // Author, Price, Valuta these are external variable functions MyBook
          // these variables are visible from the outside because they are declared as this.
          this.Author = "";
          this.Price = 0;
          this.Valuta = '';

          // MyInfo it is an external variable of the function MyBook with a set of properties
          // MyInfo is visible from the outside because it is declared as this.
          this.MyInfo =
          {
               PagesCount: 90,
               HasPictures: true
          };

          // Shops it is an external variable of the function MyBook contains an empty array
          // Shops is visible from the outside because it is declared as this.
          this.Shops = []; // shops where you can buy books

          // ShowBookName it is an external function-variable with no parameters
          // ShowBookName is visible from the outside because it is declared as this.
          this.ShowBookName = function ()
          {
               alert(BookName);
          }

          // ShowBookShops it is an external variable function with a parameter title
          // ShowBookShops is visible from the outside because it is declared as this.
          this.ShowBookShops = function (title)
          {
               alert(title + ": " + this.Shops);
               this.MyFuncHello();
          }

          // MyInnerFunc1 is an internal variable function
          // MyInnerFunc1 NOT visible from the outside because it is declared as var
          var MyInnerFunc1 = function ()
          {
               alert("Hello inner function 1");
          }

          // MyInnerFunc1 it is an internal function
          // MyInnerFunc1 NOT visible from the outside because, declared inside the function MyBook
          function MyInnerFunc2()
          {
               alert("Hello inner function 2");
          }
     }

     // MyStaticFunc it is a static function
     // MyStaticFunc is visible from the outside and is used only with the name MyBook
     MyBook.MyStaticFunc = function ()
     {
          alert("Hello static function");
     }

     // MyFuncHello it is an internal function
     // MyFuncHello NOT visible from the outside because, declared inside the function MyBook
     MyBook.prototype.MyFuncHello = function ()
     {
          alert("Hello function");
     }

     // To create a class
     var book = new MyBook("Vlastelin kolec");

     // setting values to external variables
     book.Author = "Nik Perumov";
     book.Price = 60;
     book.Valuta = "Rubles";
     book.Shops = ["Minsk", "Moscow", "London"];

     // calling an external variable function
     book.ShowBookName();
     // на экране увидим "Vlastelin kolec"

     // calling an external variable function
     book.ShowBookShops("Shops");
     // on the screen we will see "Shops: Minsk, Moscow, London"

     // call a static function
     MyBook.MyStaticFunc();
     // на экране увидим "Hello static function"

     // call an internal function
     book.MyInnerFunc1(); error: 'book.MyInnerFunc1 is not a function'

</script>

</body>
</html>

Creating an Object

The object is created through new and function name.

JavaScript Example

var book = new MyBook();

Internal and external variables

MyBook contains an internal variable BookName because, declared as var

MyBook contains external variables Author, Price, Valuta, MyInfo, Shops because, declared as this.

JavaScript

// class MyBook
function MyBook(name)
{
...
     // internal variable
     var BookName = name;

     // external variables
     this.Author = "";
     this.Price = 0;
     this.Valuta = '';

     this.MyInfo =
     {
          PagesCount: 90,
          HasPictures: true
     };

     this.Shops = [];
...
}

this. indicates that an external variable has been declared for the class MyBook.
This variable will live as long as the object MyBook.

The internal variable is declared as var BookName
will collapse immediately after exiting the function MyBook
На заметку! Переменная BookName используется внутрии функции ShowBookName.
Поэтому переменная BookName будет жить столько же сколько функция ShowBookName.
А функция ShowBookName живет столько же сколько и функция MyBook.
То есть переменная BookName будет жить столько же сколько функция MyBook

Internal and external functions

Inside MyBook we have announced a feature with the name ShowMyMessage with parameter title

JavaScript

// class MyBook
function MyBook(name)
{
     ...
     // function
     this.ShowMyMessage = function (title)
     {
          alert(title + " " + this.Name + " " + this.MyInfo.PagesCount);
     }
     ...
}

Статические функции

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{...} = объект в JavaScript заполняем из переменных класса или другим объектом. Пример: const {name, total, price} = b.myProps; | standard ES5

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Encapsulating variables (hiding variables for access) in the function (as a class) in the JavaScript | standard ES5