What is a Function in JavaScript
A JavaScript function is a block of code designed to perform a particular task. In simple terms, Functions are used to make work easy, reduce the effort of coding multiple lines for the same task which is needed to repeat multiple times.
In JavaScript function declaration and definition are done together.
OOPs stands for Object Oriented Programming which is all about creating class and objects. Class serves as a template and multiple objects can be created using the class.
Oops concept reduces code repetition. Classes are templates for creating objects.
For an example, if we see a game take it as a Racing game where we will be having multiple cars which will be running there. So in this case either we have to write codes for each car individually or else we can create a class for car and then we can use it multiple times for the other class with that class name.
A class is a self-contained, independent collection of variables and functions which work together to perform one or more specific tasks, while objects are individual instances of a class.
We can see an example given below:
References:
Introduction:- AJAX stands for Asynchronous Javascript And XML. AJAX is used for fast creating dynamic web pages. It allow web pages to be updated asynchronously by exchanging some amount of data with the server behind the scenes. It is possible to update some parts of a web page without reloading the whole page. There are many web applications that run on ajax example:- gmail,facebook,twitter,google map, youtube etc.
Understanding synchronous and asynchronous:-
Synchronous:- The synchronous request blocks the client until the operation completes.
Asynchronous:- Asynchronous request doesn’t block the client. At the time when the request is processing, user can perform another operation.
Some AJAX technologies:-
As we know ajax is not a technology but group of inter related technologies.some of the technologies is given below:
1.HTML/XHTML and CSS
2.XML and JSON
3.DOM
4.XMLHttpRequest
5.javascript
HOW AJAX WORKS:-
AJAX communicates with the server using XMLHttpRequest. The user sends the request from the UI and the javascript call goes to XMLHttpRequest object. Then the Http request is send to the server. Then the server interact with the database and data is retrived. The server sends te data to the XMLHttpRequest callback function. And HTML and CSS data is displayed on the browser.