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SepJavaScript is a prototype-based programming language which has no class like as C++, C#, Java etc. JavaScript uses functions as classes. Hence, in JavaScript we can define a class name Student as given below-
<script> function Student() { } //creating instances of class var st1 = new Student(); var st2 = new Student(); </script>
Making members public and private
You can define a private or local variable inside a class by using var keyword. When you define a variable without var keyword inside a class, it acts as a public variable.
<script> //Person class var Person = function () { var id; //private var show = function () { }; //private function this.Name = "Deepak"; //public this.Address = "Dehi"; //public this.Display = function () { //public function //do something }; }; //creating instance of Person class var person1= new Person(); // calling the person class Display method. person1.Display(); </script>
Prototype-based programming
Prototype-based programming is a style of object-oriented programming in which classes are not present, and code re-usability or inheritance is achieved by decorating existing objects which act as prototypes. This programming style is also known as class-less, prototype-oriented, or instance-based programming.
Defining constructor in JavaScript
In JavaScript, the function acts as the constructor for the instance. Function within JavaScript is defined by using function keyword followed by parentheses (). You can define a Person class with constructor as given below:
<script> var Person=function (firstname, lastname, age) { //constructor this.firstname = firstname; this.lastname = lastname; this.age = age; }; var person1 = new Person("Deepak", "Kumar", 50); </script>
Different ways to create object/instance
In JavaScript, you can create object in two different ways as given below-
Using Constructor function
You can create the object in JavaScript, by using new keyword and constructor function as given below-
<script> function Person(firstname, lastname, age) { this.firstname = firstname; this.lastname = lastname; this.age = age; } var person1 = new Person("Deepak", "Kumar", 50); var person2 = new Person("Manu", "chauhan", 21); </script>
Using Object initializer
You can also create the object in JavaScript, by using object initializer as given below-
<script> person1 = new Object(); person.firstname = "Deepak"; person.lastname = "Kumar"; person.age = 50; //Or person1 = { firstname: "Deepak", lastname: "Kumar", age: 50 }; </script>
What do you think?
I hope you will enjoy the prototype while programming with JavaScript. I would like to have feedback from my blog readers. Your valuable feedback, question, or comments about this article are always welcome.
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