Ajax interview questions and Answers
Asynchronous JavaScript and XML is a new age and advanced set of development techniques popular among developers for building websites and web applications faster better and more interactive. It uses XML, CSS, HTML and JavaScript. The core function of AJAX is to update web content asynchronously, which means a user’s web browser doesn’t require to reload an entire web page when only a small portion of page content needs to be changed. It’s neither a tool nor a programming language; AJAX is a concept, a client-side script that communicates to and from a database/server without require of a complete page refresh or a Postback. The demand for AJAX is quite popular among businesses due to its versatility. We will discuss a set of most asked AJAX interview questions relevant to them further here.
Most Frequently Asked Ajax interview questions
Here in this article, we will be listing frequently asked Ajax interview questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.
AJAX is a technique used to create dynamic and fast web pages and applications. It allows web pages to be updated asynchronously by interchanging small amounts of data with the backend server. It communicates with the server with the XMLHttpRequest object.
AJAX has plenty of features and advantages for its users. Few of the best ones are described below:-
- It allows asynchronous calls to a web server.
- Minimal data transfer and network utilization quicker operation.
- Limited processing on the server
- AJAX applications are very responsive due to the asynchronous on the client
AJAX allows web pages to be modified asynchronously. It combines several programming tools primarily JavaScript, Extensible Markup Language – XML, dynamic HTML, CSS, DOM and XMLHttpRequest. This suggests the name AJAX here.
AJAX has few limitations for its users. Here are a few of them:-
- Can’t use forward and back buttons to navigate between various page states.
- Users can’t bookmark specific state here.
- Major search engines don’t index data loaded through AJAX.
- Users without JavaScript support or disabled JavaScript won’t be able to use the functionality that developers provide through AJAX.
It uses the following technologies:-
- HTML & CSS: Used for presentation
- DOM: Used for data interaction and dynamic display
- JSON or XML: Used for carrying data from and to server
- XMLHttpRequest: Used for asynchronous communication between server and client.
- JSP or ASP: Used for server-side
- JavaScript: Used to bring all the above technologies together.
Here are few most asked AJAX interview questions by global interviewers.
Developers use JSON to pass the updates made in AJAX between the client and the server. We can take websites with live updates can be considered as an example of AJAX with JSON. It directly assigns data to the elements present in DOM of the web pages.
The cache: false is used by developers to prevent all future AJAX requests from being cached, regardless of which jQuery method they use. We can use $.ajaxSetup({cache:false}); to apply the technique for all AJAX functions.
To improve AJAX call performance, follow these steps:-
- Reduce the AJAX request numbers.
- Wisely elect the event on which AJAX request triggers.
- Appropriately use GET requests.
- Reduce the amount of data transmitted.
- Secure data using Caching.
In AJAX, Synchronous Request ( async: false ) is used to stop JavaScript processing the program until a result has been obtained from the server side. In some situations, the Synchronous script is mandatory.
If you are looking out for best AJAX interview questions for experienced, follow this set.
| S.no | AJAX | JavaScript |
|---|---|---|
| 1. | AJAX is a technology, not a programming language. | JavaScript is a programming language used to complete client-side tasks in web development. |
| 2. | AJAX is a part of JavaScript programming. | JavaScript is used to control and manage a web page once downloaded. |
| S.no | synchronous | asynchronous |
|---|---|---|
| 1. | Synchronous or ( async: false ) script stops the program and waits for the server to send back a reply before continuing. | Asynchronous or ( async: exact) script allows the web page to continue to be processed and will handle the reply when and if it arrives. |
| S.no | AJAX | JSON |
|---|---|---|
| 1. | AJAX is a group of technologies. | JavaScript Object Notation or JSON is a text-based open standard designed for human-readable data interchange. |
| 2. | It refers to receiving and sending data between a web browser’s objects and another source. | JSON is a data and can be sent via AJAX but can be used for other purposes besides AJAX. |
In AJAX, the XMLHttpRequest (XHR) is an API that can be used by JScript, JavaScript, VB Script and other available web browser scripting languages to manipulate and transfer XML data from and to a web server using HTTP, bridging an independent connection channel between a webpage’s server side and client side.
Know the basics of AJAX with these specially curated AJAX interview questions and answers.
The primary use of AJAX is to allow the client side of an application to communicate with the server side of the application effectively. It’s the first technique available in which the client side of a web application to communicate directly with the server.
There are five types of active states available in AJAX. Here are those:
- request not initialized - ready state 0
- server connection established - ready state 1
- request received - ready state 2
- processing request - ready state 3
- request finished, and the response is ready - ready state 4
To know the status of an AJAX request, developers use ready State. It allows users to determine the request status. It the value comes 4, then the application has been completed, and the response is sent to the browser.
It’s an asynchronous request initialized by the browser that doesn’t directly result in a page transition. In an AJAX call, AJAX communicates with the server using the XMLHttpRequest object.
Ajax requests produce a wide variety of distinctive occasions that you can subscribe to. Here's a full listing of the activities and in what order they are triggered.
There are 2 types of events in Ajax
- Local Events: Local Events are callbacks that you can subscribe to inside the Ajax request object.
- Global Events: Global events are triggered on the document, calling any handlers who may be listening.
Example of Local Events
$.ajax({
beforeSend: function(){
},
complete: function(){
}
});Example of Global Events
$.ajax({
url: "bestinterviewquestion.html",
global: false,
});
Script Manager, as the identify suggests is used to managing the client-side script of Ajax. Since Ajax makes use of JavaScript, there desires to be a mediator to control this script and hinder a precise model to a browser. A Script supervisor is existing on each and every web page the place Ajax is used to allow the Ajax Libraries. These Libraries, in turn, helps to put into effect the Core Functionality of Ajax: Partial rendering.
There are 2 types of post back in AJAX.
- Asynchronous - It does not block the client.
- Synchronous - It blocks the client until the operation completes.