AJAX interview questions and answers

AJAX Interview Questions and Answers in 2022

Ajax interview questions and answers 2022

AJAX interview questions and answers

A list of frequently asked AJAX interview questions and answers are given below.

AJAX tutorial and examples for AJAX technology for beginners and professionals.

AJAX is acronym for Asynchronous JavaScript. It is  groups of  technologies like JavaScript, DOM, XML, HTML/XHTML, CSS, XMLHttpRequest etc.

 

ajax

AJAX allows you to send and receive data asynchronously without reloading the web page. So it is fast.

AJAX allows sending only important information to the server, not the entire page. So only valuable data from the client-side is routed to the server-side. It makes your application interactive and faster.

 

1) What is AJAX

AJAX stands for Asynchronous JavaScript and XML. It is groups of related technologies used to display data asynchronously. In other words, it sends and retrieves data without reloading the web page. More details.

 

2) What are the advantages of AJAX

  • Quick Response
  • Bandwidth utilization
  • The user is not blocked until data is retrieved from the server.
  • It allows us to send only important data to the server.
  • It makes the application interactive and faster.

 

3) What are the disadvantages of AJAX

  • Dependent on JavaScript
  • Security issues
  • Debugging is difficult

 

4) What are the real web applications of AJAX currently running in the market

  • Twitter
  • Facebook
  • Gmail
  • Javatpoint
  • Youtube

 

5) What are the security issues with AJAX

  • AJAX source code is readable
  • Attackers can insert the script into the system

 

6) What is the difference between synchronous and asynchronous requests

Synchronous request blocks the user until a response is retrieved whereas asynchronous doesn’t block the user. More details.

Synchronous Request

synchronous request

Asynchronous Request

asynchronous request

 

7) What are the technologies used by AJAX

  • HTML/XHTML and CSS – These technologies are used for displaying content and style.
  • DOM – It is used for dynamic display and interaction with data.
  • XML – It is used for carrying data to and from the server
  • XMLHttpRequest – It is used for asynchronous communication between client and server.
  • JavaScript – It is used mainly for client-side validation

 

8) What is the purpose of XMLHttpRequest

  • It sends data in the background to the server.
  • It requests data from the server.
  • It receives data from the server.
  • It updates data without reloading the page.
  • More details.

 

9) What are the properties of XMLHttpRequest

  • The important properties of the XMLHttpRequest object are given below
  • onReadyStateChange – It is called whenever ready state attribute changes.
  • readyState – It represents the state of the request.
  • responseText – It returns response as text.
  • responseXML – It returns response as XML.
  • status – It returns the status number of a request.
  • statusText – It returns the details of status.

 

10) What are the important methods of XMLHttpRequest

  • abort() – It is used to cancel the current request.
  • getAllResponseHeaders() – It returns the header details.
  • getResponseHeader() – It returns the specific header details.
  • open() – It is used to open the request.
  • send() – It is used to send the request.
  • setRequestHeader() – It adds request header.

 

11) What are the types of open() methods used XMLHttpRequests

  • open(method, URL) – It opens the request specifying get or post method and URL.
  • open(method, URL, async) – It is the same as above but specifies asynchronous or not.
  • open(method, URL, async, username, password) – It is the same as above but specifies the username and password.

 

12) What are the types of send() method used for XMLHttpRequest

  • send() – It sends get request
  • send(string) – It sends post request.

 

13) What is the role of a callback function in AJAX

The callback function passes a function as a parameter to another function. If we have to perform various AJAX tasks on a website, then we can create one function for executing XMLHttpRequest and a callback function to execute each AJAX task.

how ajax works, the flow of ajax

 

14) What is JSON in AJAX

JSON stands for JavaScript Object Notation. In AJAX, it is used to exchanges data between a browser and a server. It is easy to understand, and data exchange is faster than XML. It supports array, object, string, number, and values.

request.onreadystatechange  = function(){

if (request.readyState == 4  )    {

var jsonObjs = JSON.parses(requests.responseTexts);//JSON.parse() returns JSON object

document.getElementById(“date”).innerHTML =  jsonObj.date;

document.getElementById(“time”).innerHTML = jsonObj.time;

}       }

 

15) What are the tools for debugging AJAX applications

There are several tools for debugging AJAX applications.

  • Firebug for Mozilla Firefox
  • Fiddler for IE (Internet Explorer)
  • JavaScript HTML Debugger
  • MyEclipse AJAX Tools
  • Script Debugger

AJAX interview questions and answers

16) What are the types of posts back in AJAX

There are two types of posts back in AJAX.

Synchronous Postback – It blocks the client until the operation completes.

how synchronous request works

Asynchronous Postback – It doesn’t block the client.

how asynchronous request works

 

17) What are the different ready states of a request in AJAX

There 4 and more ready states of a request in AJAX.

0 means UNOPENED

  • 1 means OPENED
  • 2 means HEADERS_RECEIVED
  • 3 means LOADING
  • 4 means DONE

 

18) What are the common AJAX frameworks

Dojo Toolkit

  • YUI
  • Google Web Toolkit (GWT)
  • Spry
  • MooTools
  • Prototype

 

19) How can you test the AJAX code?

A Unit is an open-source unit testing framework for client-side JavaScript. It is required to create test cases. The unit test case is a code that ensures that the program logic works as expected.

 

AJAX Tutorial

AJAX is a web development technique for creating interactive web applications. If you know JavaScript, HTML, CSS, and XML, then you need to spend just one hour to start with AJAX.

 

Why Learn Ajax?

AJAX stands for Asynchronous JavaScript and XML. AJAX is a new technique for creating better, faster, and more interactive web applications with the help of XML, HTML, CSS, and JavaScript.

  • Ajax uses XHTML for content, CSS for presentation, along with Document Object Model and JavaScript for dynamic content display.
  • Conventional web applications transmit information to and from the server using synchronous requests. It means you fill out a form, hit submit, and get directed to a new page with new information from the server.
  • With AJAX, when you hit submit, JavaScript will make a request to the server, interpret the results, and update the current screen. In the purest sense, the user would never know that anything was even transmitted to the server.
  • XML is commonly used as the format for receiving server data, although any format, including plain text, can be used.
  • AJAX is a web browser technology independent of web server software.
  • A user can continue to use the application while the client program requests information from the server in the background.
  • Intuitive and natural user interaction. Clicking is not required, mouse movement is a sufficient event trigger.
  • Data-driven as opposed to page-driven.

 

Top Internet Application Technology

AJAX is the most viable Rich Internet Application (RIA) technology so far. It is getting tremendous industry momentum and several tool kit and frameworks are emerging. But at the same time, AJAX has browser incompatibility and it is supported by JavaScript, which is hard to maintain and debug.

 

AJAX is Based on Open Standards

AJAX is based on the following open standards −

  • Browser-based presentation using HTML and Cascading Style Sheets (CSS).
  • Data is stored in XML format and fetched from the server.
  • Behind-the-scenes data fetches using XMLHttpRequest objects in the browser.
  • JavaScript to make everything happen.

 

Audience

This tutorial will be useful for web developers who want to learn how to create interactive web pages improve their speed and usability using AJAX.

Prerequisites

It is highly recommended that you are familiar with HTML and JavaScript before attempting this tutorial.

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