JavaScript-thiskeyword - (4)

-

 


👉"this" keyword


✅Use of "this" keyword

Syntax - this.x = 10;



Basically, DOM hierarchy gets created as shown above and Javascript has access to this DOM hierarchy.

When the browser parses HTML, it creates a DOM
inside it. On the top, there is a window object, inside window, document gets created and finally, form gets generated within document.

"this" refers to the top window object of your browser.

When you create any type of variable or object in javascript, it gets attached to the window object.

var x = 10;
alert(window.x);
alert(this.x);  
//Both alerts refer to the same variable and display the same output.

Comments

Post a Comment

Popular posts from this blog

Javascript-OOPs(Part2)-AbstractionAndEncapsulation- (8)

-
Image
    👉 Javascript with OOPs (Abstraction and Encapsulation) Abstraction is showing what's necessary and Encapsulation is hiding the complexity. For ex, if we are making calls to the server, we may have methods like: this.CreateConnection = function() {} this.CreateHttpObject = function() {} Showing these methods to the user who is using this component may increase the complexity of the component. User may have to call          cust.CreateConnection();          cust. CreateHttpObject();          cust.Submit(); So  CreateConnection and CreateHttpObject has to be private, but the time you declare the methods using "this" keyword, it becomes public. Below example solves this problem by creating private functions. If user makes a call to CreateConnection or CreateHttpObject, he will  receive "Not Found" error. *Create private methods function Customer(){        function CreateConnection() {};       function CreateHttpObject () {};       this.submit = function() {    
Read more

Javascript-OOPs(Part4)-Polymorphism- (10)

-
Image
   👉 Javascript with OOPs (Polymorphism) Polymorphism is possible only with strongly typed languages, we cannot implement it in Javascript since we cannot declare strongly typed variables, and datatypes of variables are decided at runtime. We have achieved a bit of polymorphism while implementing inheritance, where in "cust" object first refers to the "Customer" class and then to the "CustomerChild" class, but still direct polymorphism is not available. Javascript variables are dynamic and they are created based on the datatype of the right-hand side value. To summarize: 1)You can create a class by using a function. You have a new keyword to create an instance. 2)You can define private and public methods by using/not using the "this" keyword. 3)Function inside a function is a closure. Closures are the core while implementing classes and objects in javascript. 4)Use Closures to create private methods, if you want to expose the method use "th
Read more

Javascript-OOPs(Part1)-Objects - (7)

-
Image
    👉 Javascript with OOPs New javascript specification ES6 introduced "Javascript classes" though it uses "function" internally,  previous frameworks don't allow the "class" keyword, and the below example creates a class using Javascript functions. *Create class and object function Customer(){ //class template } var cust = new Customer(); //object *Create Method and Properties function Customer(){        this.CustomerName = "";       this.CustomerCode = "";       this.submit = function() {            alert("Submit" + this.CustomerName + " " +                       this.CustomerCode); } var cust = new Customer();  cust.CustomerName = "John"; cust.CustomerCode = "1001"; cust.Submit(); The above example defines only variables, which are not secure and not good for developing business components. To define properties in javascript, we don't have direct "getter" and "setter&quo
Read more